Method of forming patterns

ABSTRACT

A method of forming patterns includes (a) coating a substrate with a resist composition for negative development to form a resist film having a receding contact angle of 70 degrees or above with respect to water, wherein the resist composition for negative development contains a resin capable of increasing the polarity by the action of an acid and becomes more soluble in a positive developer and less soluble in a negative developer upon irradiation with an actinic ray or radiation, (b) exposing the resist film via an immersion medium, and (c) performing development with a negative developer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-In-Part of U.S. application Ser. No.12/959,147, filed Dec. 2, 2010 (now allowed), which is a ContinuationApplication of U.S. application Ser. No. 12/137,371, filed Jun. 11,2008, now U.S. Pat. No. 8,017,298, which claims priority from JapaneseApplication No. 2007-155323, filed Jun. 12, 2007; all of which arehereby incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of forming patterns, which isusable in a production process of semiconductors, such as ICs,manufacturing of circuit boards for liquid crystal displays or thermalheads, and other lithography processes of photofabrication. Morespecifically, the invention is concerned with a method of formingpatters by using a resist composition for negative development and anegative developer preferable used in the lithography process performinglight exposure by means of immersion-type projection exposure apparatus.

2. Description of the Related Art

As semiconductor devices have become increasingly finer, progress hasbeen made in developing exposure light sources of shorter wavelengthsand projection lenses having higher numerical apertures (higher NAs). Upto now, steppers using as light sources ArF excimer laser with awavelength of 193 nm and having NA of 1.35 have been developed. Asgenerally well known, relationships of these factors to resolution anddepth of focus can be given by the following expressions;

(Resolution)=k ₁·(λ/NA)

(Depth of Focus)=±k ₂ ·λ/NA ²

where λ is the wavelength of an exposure light source, NA is thenumerical aperture of a projection lens, and k₁ and k₂ are coefficientsconcerning a process.

As an art of heightening the resolution in an optical microscope, themethod of filling the space between a projection lens and a testspecimen with a liquid having a high refractive index (hereinafterreferred to as an immersion liquid or an immersion medium), or theso-called immersion method, has hitherto been known.

This “immersion effect” can be explained as follows. When the immersionmethod is applied, the foregoing resolution and depth of focus can begiven by the following expressions;

(Resolution)=k ₁·(λ₀ /n)/NA ₀

(Focal depth)=±k ₂·(λ₀ /n)/NA ₀ ²

where λ₀ is the wavelength of an exposure light source in the air, n isthe refractive index of an immersion liquid relative to the air and NA₀is equal to sin θ when the convergent half angle of incident rays isrepresented by θ. That is to say, the effect of immersion is equivalentto the use of exposure light with a 1/n wavelength. In other words,application of the immersion method to a projection optical systemhaving the same NA value can multiply the focal depth by a factor of n.

This art is effective on all shapes of patterns, and besides, it can beused in combination with super-resolution techniques under study atpresent, such as a phase-shift method and an off-axis illuminationmethod.

Examples of apparatus utilizing this effect for transfer of fine circuitpatterns in semiconductor devices are disclosed in Patent Document 1(JP-A-57-153433) and Patent Document 2 (JP-A-7-220990), but thesedocuments have no description of resist suitable for immersionlithography.

Recent progress of immersion lithography is reported, e.g., inNon-patent Document 1 (Proc. SPIE, 4688, 11 (2002)), Non-patent Document2 (J. Vac. Sci. Technol., B 17 (1999)), Patent Document 3 (WO2004/077158) and Patent Document 4 (WO 2004/068242). In the case whereArF excimer laser is used as a light source, purified water (refractiveindex at 193 nm: 1.44) is the most promising immersion liquid in pointof not only handling safety but also transmittance and refractive indexat 193 nm, and actually applied in mass production too. On the otherhand, it is known that immersion exposure using a medium of a higherrefractive index as immersion liquid can offer higher resolution(Non-patent Document 3: Nikkei Microdevices, April in 2004).

For the purpose of supplementing the sensitivity of resist, which hasbeen reduced by light absorption from the resist for KrF excimer laser(248 nm) onward, the image formation method referred to as a chemicalamplification technique has been adopted as a method of patterningresist. To illustrate an image formation method utilizing chemicalamplification by a positive-working case, images are formed in such aprocess that exposure is performed to cause decomposition of an acidgenerator in the exposed areas, thereby generating an acid, andconversion of alkali-insoluble groups into an alkali-soluble groups byutilizing the acid generated as a reaction catalyst is caused by bakeafter exposure (PEB: Post Exposure Bake) to allow the removal of exposedareas by an alkaline developer.

Since application of immersion lithography to chemical amplificationresist brings the resist layer into contact with an immersion liquid atthe time of exposure, it is pointed out that the resist layer suffersdegradation and ingredients having adverse effects on the immersionliquid are oozed from the resist layer. More specifically, PatentDocument 4 (WO 2004/068242) describes cases where the resists aimed atArF exposure suffer changes in resist performance by immersion in waterbefore and after the exposure, and indicates that such a phenomenon is aproblem in immersion lithography.

In addition, there is apprehension that, when an immersion exposureprocess is carried out using a scanning immersion photolithographymachine, reduction in exposure speed occurs unless an immersion liquidmoves on with movements of a lens, and has an adverse effect onproductivity. When the immersion liquid is water, it is expect thathydrophobic resist film is better in following capability of water.However, the hydrophobicity imparted to resist film brings aboutunfavorable situations, such as an increase in amount of resist residues(referred to as “scum” too) developed, and degrades image quality ofresist. Therefore, it is desirable to remedy the matters mentionedabove.

At present, an aqueous alkali developer containing 2.38 mass % of TMAH(tetramethylammonium hydroxide) has broad use as developers for g-ray,i-ray, KrF, ArF, EB and EUV lithographic processes.

As a developer other than the aqueous alkali developer, the developerused for performing development by dissolving exposed areas of a resistmaterial reduced in molecular weight through cleavage of its polymerchains by exposure to radiation, and that characterized by having atleast two functional groups of more than one kind chosen from an aceticacid group, a ketone group, an ether group or a phenyl group and amolecular weight of 150 or above, is disclosed, e.g., in Patent Document5 (JP-A-2006-227174). In addition, the developers used for performingdevelopment by dissolving exposed areas of specified resist materialscontaining fluorine atoms and chosen from supercritical fluids,halogenated organic solvents or non-halogenated organic solvents aredisclosed in Patent Document 6 (JP-T-2002-525683, the term “JP-T” asused herein means a published Japanese translation of a PCT patentapplication) and Patent Document 7 (JP-T-2005-533907).

However, as semiconductor devices become finer, it becomes exceedinglydifficult to find suitable combinations of resist composition, developerand so on for formation of totally high-quality patterns. No matter howdifficult it may be, it has been required to find pattern formationmethods applicable suitably to immersion lithography, which can ensure,e.g. reduction in scum appearing after development, satisfactory lineedge roughness, high in-plane uniformity of line width, and goodfollowing capability of an immersion liquid.

SUMMARY OF THE INVENTION

The invention aims to solve the aforesaid problems and to provide apattern formation method that allows reduction in scum appearing afterdevelopment, and besides, that can ensure reduced line edge roughness,enhanced in-plane uniformity of line width and satisfactory followingcapability of an immersion liquid, thereby achieving consistentformation of high-accuracy fine patterns for fabrication ofhigh-integration, high-precision electronic devices.

The following are aspects of the invention, and thereby the aforesaidaims of the invention are accomplished.

<1> A method of forming patterns, comprising:

(a) coating a substrate with a resist composition for negativedevelopment to form a resist film having a receding contact angle of 70degrees or above with respect to water, wherein the resist compositionfor negative development contains a resin capable of increasing thepolarity by the action of an acid and becomes more soluble in a positivedeveloper and less soluble in a negative developer upon irradiation withan actinic ray or radiation,

(b) exposing the resist film via an immersion medium, and

(c) performing development with a negative developer.

<2> The method of forming patterns of <1>, wherein

the resist composition for negative development comprises:

(A) said resin capable of increasing the polarity by the action of anacid, which becomes more soluble in a positive developer and lesssoluble in a negative developer upon irradiation with an actinic ray orradiation,

(B) a compound capable of generating an acid upon irradiation with anactinic ray or radiation,

(C) a solvent, and

(D) a resin having at least either a fluorine atom or a silicon atom.

<3> A method of forming patterns, comprising:

(a′) coating a substrate with a resist composition for negativedevelopment to form a resist film, wherein the resist compositioncontains a resin capable of increasing the polarity by the action of anacid and becomes more soluble in a positive developer and less solublein a negative developer upon irradiation with an actinic ray orradiation,

(b) exposing the resist film via an immersion medium, and

(c) performing development with a negative developer.

wherein

the resist composition for negative development comprises:

(A) said resin capable of increasing the polarity by the action of anacid, which becomes more soluble in a positive developer and lesssoluble in a negative developer upon irradiation with an actinic ray orradiation,

(B) a compound capable of generating an acid upon irradiation with anactinic ray or radiation,

(C) a solvent, and

(D) a resin having at least either a fluorine atom or a silicon atom.

<4> The method of forming patterns of <2> or <3>, wherein

the resin (D) has a group represented by the following formula (F3a):

wherein

each of R_(62a) and R_(63a) independently represents an alkyl group atleast one hydrogen atom of which is substituted with a fluorine atom,and R_(62a) and R_(63a) may combine with each other to form a ring, and

R_(64a) represents a hydrogen atom, a fluorine atom or an alkyl group.

<5> The method of forming patterns of any of <2> to <4>, wherein theresin (D) has a group represented by any of the following formulae(CS-1) to (CS-3):

wherein

each of R₁₂ to R₂₆ independently represents a straight-chain alkylgroup, a branched alkyl group, or a cycloalkyl group,

each of L₃ to L₅ represents a single bond or a divalent linkage group,and

n represents an integer of 1 to 5.

<6> The method of forming patterns of any of <1> to <5>, wherein thenegative developer in the process (c) of performing development containsan organic solvent.<7> The method of forming patterns of any of <1> to <6>, furthercomprising:

(d) performing development with a positive developer.

Furthermore, preferred embodiments of the invention are described below.

<8> The method of forming patterns of any of <1> to <7>, wherein thenegative developer in the process (c) of performing development containsat least one kind of solvent selected from organic solvents having vaporpressures of 5 kPa or below at 20° C.<9> The method of forming patterns of <8>, wherein the organic solventshaving vapor pressures of 5 kPa or below at 20° C. are ketone solvents,ester solvents or ether solvents.<10> The method of forming patterns of <8> or <9>, wherein the organicsolvents having vapor pressures of 5 kPa or below at 20° C. are estersolvents.<11> The method of forming patterns of any of (8) to (10), wherein theorganic solvents having vapor pressures of 5 kPa or below at 20° C. arebutyl acetate.<12> The method of forming patterns of any of <1> to <11>, furthercomprising: (e) performing cleaning with a rinse liquid containing anorganic solvent subsequently to the process (c) of performing.<13> The method of forming patterns of <12>, wherein the rinse liquid inthe process (e) of performing cleaning contains at least one kind oforganic solvent selected from hydrocarbon solvents, ketone solvents,ester solvents, alcohol solvents, amide solvents or ether solvents.<14> The method of forming patterns of <12> or <13>, wherein the rinseliquid in the process (e) of performing cleaning contains at least onekind of organic solvent selected from ester solvents or alcoholsolvents.<15> The method of forming patterns of any of <12> to <14>, wherein therinse liquid in the process (e) of performing cleaning contains amonohydric alcohol.<16> The method of forming patterns of any of <12> to <15>, wherein therinse liquid in the process (e) of performing cleaning contains at leastone ingredient of the negative developer in the process (c) ofperforming development.<17> The method of forming patterns of any of <1> to <16>, wherein theprocess (c) of performing development comprises a process of feeding thenegative developer onto a surface of the substrate while spinning thesubstrate.<18> The method of forming patterns of any of <12> to <17>, wherein theprocess (e) of performing cleaning comprises a process of feeding therinse liquid onto a surface of the substrate while spinning thesubstrate.<19> The method of forming patterns of <7>, wherein the positivedeveloper in the process (d) of performing development contains anaqueous solution of at least one kind of amine compound selected fromprimary amine compounds, secondary amine compounds tertiary aminecompounds or quaternary amine compounds.<20> The method of forming patterns of <19>, wherein the positivedeveloper in the process (d) of performing development contains anaqueous solution of tetramethylammonium hydroxide.<21> The method of forming patterns of <19> or <20>, wherein thepositive developer contains the amine compound in a concentrationranging from 0.01 to 20 weight % based on a total weight of the positivedeveloper.<22> The method of forming patterns of any of <7>, <19> to <21>, furthercomprising:

(f) performing rinsing, after the process (d) of performing developmentwith a positive developer.

<23> The method of forming patters of <22>, wherein a rinsed fluid inthe process (0 of performing rinsing is purified water.<24> The method of forming patterns of any of <1> to <23>, wherein theprocess of (b) exposing the resist film is performed with light having awavelength of 200 nm or shorter.<25> The method of forming patterns of any of <1> to <24>, wherein theimmersion medium of the process of (b) exposing the resist film iswater.<26> The method of forming patterns of any of <1> to <25>, furthercomprising:

(g) performing heating, after the process (b) of exposing the resistfilm.

<27> The method of forming patterns of any of <2> to <26>, wherein

the resin (D) of the resist composition is a resin stable to an acid andinsoluble in an alkali developer.

<28> The method of forming patterns of <27>, wherein

the resin (D) of the resist composition is a resin soluble in thenegative developer.

<29> The method of forming patterns of any of <2> to <28>, wherein

the resin (D) of the resist composition contains repeating units havinga alkali-soluble group or a group capable of increasing the solubilityto the developer by the action of an acid or an alkali in a totalproportion of 20 mole % or below with respect to the total repeatingunits constituting the resin (D).

<30> The method of forming patterns of <2> to <29>, wherein

the resin (D) is contained in an amount of 0.1 to 5 mass % based on thetotal solids in the resist composition.

<31> The method of forming patterns of any of <2> to <30>, wherein

the resin (D) of the resist composition is a resin selected from thefollowing resins (D-1) to (D-6):

(D-1) a resin that has (a) a repeating unit containing a fluoroalkylgroup,

(D-2) a resin that has (b) a repeating unit containing a trialkylsilylgroup or a cyclic siloxane structure,

(D-3) a resin that has (a) a repeating unit containing a fluoroalkylgroup and (c) a repeating unit containing a branched alkyl group, acycloalkyl group, a branched alkenyl group, a cycloalkenyl group or anaryl group,

(D-4) a resin that has (b) a repeating unit containing a trialkylsilylgroup or a cyclic siloxane structure and (c) a repeating unit containinga branched alkyl group, a cycloalkyl group, a branched alkenyl group, acycloalkenyl group or an aryl group,

(D-5) a resin that has (a) a repeating unit containing a fluoroalkylgroup and (b) a repeating unit containing a trialkylsilyl group or acyclic siloxane structure, and

(D-6) a resin that has (a) a repeating unit containing a fluoroalkylgroup, (b) a repeating unit containing a trialkylsilyl group or a cyclicsiloxane structure and (c) a repeating unit containing a branched alkylgroup, a cycloalkyl group, a branched alkenyl group, a cycloalkenylgroup or an aryl group.

<32> The method of forming patterns of any of <2> to <31>, wherein

the resin (D) of the resist composition has a repeating unit representedby the following formula (Ia):

wherein

Rf represents a hydrogen atom, a fluorine atom or an alkyl group atleast one hydrogen atom of which is substituted with a fluorine atom,

R₁ represents an alkyl group, and

R₂ represents a hydrogen atom or an alkyl group.

<33> The method of forming patterns of any of <2> to <32>, wherein

the resin (D) of the resist composition has a repeating unit representedby the following formula (II) and a repeating unit represented by thefollowing formula (III):

wherein Rf represents a hydrogen atom, a fluorine atom or an alkyl groupat least one hydrogen atom of which is substituted with a fluorine atom,

R₃ represents an alkyl group, a cycloalkyl group, an alkenyl group or acycloalkenyl group,

R₄ represents an alkyl group, a cycloalkyl group, an alkenyl group, acycloalkenyl group, a trialkylsilyl group or a group having a cyclicsiloxane structure,

L₆ represents a single bond or a linkage group,

m is a numeric value of from 0 to 100, and n is a numeric value of 0 to100.

<34> The method of forming patterns of any of <2> to <33>, wherein theresin (A) of the resist composition is a resin having an alicyclichydrocarbon structure.<35> The method of forming patterns of any of <2> to <34>, wherein theresin (A) of the resist composition is a resin having, in its sidechain, an alicyclic hydrocarbon-containing partial structure representedby any of the following formulae (pI) to (pV);

wherein

R₁₁ represents a methyl group, an ethyl group, an n-propyl group, anisopropyl group, an n-butyl group, an isobutyl group or a sec-butylgroup,

Z represents atoms forming a cycloalkyl group together with the carbonatom,

each of R₁₂ to R₁₆ independently represent a 1-4C straight-chain orbranched alkyl group, or a cycloalkyl group, provided that at least oneof R₁₂ to R₁₄, or either R₁₅ or R₁₆ represents a cycloalkyl group,

each of R₁₇ to R₂₁ independently represents a hydrogen atom, a 1-4Cstraight-chain or branched alkyl group or a cycloalkyl group, providedthat at least one of R₁₇ to R₇₁ represents a cycloalkyl group, andbesides, either R₁₉ or R₂₁ represents a 1-4C straight-chain or branchedalkyl group or a cycloalkyl group; and

each of R₂₂ to R₂₅ independently represent a hydrogen atom, a 1-4Cstraight-chain or branched alkyl group or a cycloalkyl group, providedthat at least one of R₂₂ to R₂₅ represents a cycloalkyl group, and R₂₃and R₂₄ may combine with each other to form a ring.

<36> The method of forming patterns of any of <2> to <35>, wherein

the resin (A) of the resist composition has its weight average molecularweight in a range of 1,000 to 200,000.

<37> The method of forming patterns of any of <34> to <36>, wherein theresin (A) of the resist composition is an alicyclichydrocarbon-containing acid-decomposable resin having a lactonestructure.<38> The method of forming patterns of any of <1> to <37>, wherein

the resist composition further contains a basic compound.

<39> The method of forming patterns of any of <1> to <38>, wherein

the resist composition further contains at least one of afluorine-containing surfactant and a silicon-containing surfactant.

<40> The method of forming patterns of any of <2> to <39>, wherein

the solvent (C) is a mixture of two or more solvents including propyleneglycol monomethyl ether acetate.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is schematic diagrams showing relations of exposure amounts topositive development and negative development, respectively, accordingto methods currently in use.

FIG. 2 is a schematic diagram illustrating a pattern formation method inwhich a combination of positive development and negative development isused.

FIG. 3 is a schematic diagram showing a relation of exposure amounts tothe positive development and negative development.

FIG. 4 is a diagrammatic illustration of a method for evaluatingfollowing capability of water.

DETAILED DESCRIPTION OF THE INVENTION

Best modes for carrying out the invention are described below.

Incidentally, the term “group (atomic group)” used in this specificationis intended to include both unsubstituted and substituted ones whenneither a word of substituted nor a word of unsubstituted is addedthereto. For instance, the term “an alkyl group” is intended to includenot only an alkyl group having no substituent (an unsubstituted alkylgroup) but also an alkyl group having a substituent or substituents (asubstituted alkyl group).

To begin with, explanations for terms used in this specification aregiven. There are two modes of pattern formation, a positive mode and anegative mode, and both modes utilize a change caused in developersolubility of resist film by chemical reaction for which exposure tolight acts as a trigger, and more specifically, a case where exposedportions dissolve in a developer is referred to as the positive mode,and a case where non-exposed portions dissolve in a developer isreferred to as the negative mode. As to developers used therein, thereare two types of developers, a positive developer and a negativedeveloper. The term “positive developer” is defined as a developerallowing selective dissolution and removal of portions given exposureamounts (which are shown by a dotted line in FIG. 1) above a certainthreshold value as shown by a solid line in FIG. 1, while the term“negative developer” is defined as a developer allowing selectivedissolution and removal of portions given exposure amounts below theaforementioned certain threshold value. The development process using apositive developer is referred to as positive development (or a positivedevelopment process too), and the development process using a negativedeveloper is referred to as negative development (or a negativedevelopment process too). The term multiple development (or a multipledevelopment process) refers to the development mode utilizing acombination of the development process using a positive developer andthe development process using a negative developer. In the invention, aresist composition used in negative development is referred to as aresist composition for negative development, and a resist compositionused in multiple development is referred to as a resist composition formultiple development. The simple wording “a resist composition” as usedhereinafter indicates a resist composition for negative development. Theterm “a rinse liquid for negative development” means a rinse liquidwhich contains an organic solvent and is used in a cleaning processafter a negative development process.

As an art suitable for immersion lithography-utilized pattern formation,the invention provides a new pattern formation method including acombination of (a) coating a substrate with a resist composition fornegative development to form a resist film having a receding contactangle of 70 degrees or above with respect to water, wherein the resistcomposition for negative development contains a resin capable ofincreasing the polarity by the action of an acid and becomes moresoluble in a positive developer and less soluble in a negative developerupon irradiation with an actinic ray or radiation, (b) exposing theresist film via an immersion medium and (c) performing development witha negative developer which, as shown in FIG. 2, allows selectivedissolution and removal of portions exposed in exposure amounts of nohigher than a specified threshold value (b), or a new pattern formationmethod including a combination of (a′) coating a substrate with a resistcomposition for negative development to form a resist film, wherein theresist composition contains a resin capable of increasing the polarityby the action of an acid and becomes more soluble in a positivedeveloper and less soluble in a negative developer upon irradiation withan actinic ray or radiation, (b) exposing the resist film via animmersion medium and (c) performing development with a negativedeveloper, with the resist composition for negative developmentcontaining (A) a resin capable of increasing the polarity by the actionof an acid and becoming more soluble in a positive developer and lesssoluble in a negative developer upon irradiation with an actinic ray orradiation, (B) a compound capable of generating an acid upon irradiationwith an actinic ray or radiation, (C) a solvent and (D) a resin havingat least either a fluorine atom or a silicon atom.

For carrying out the invention, (i) a resist composition for negativedevelopment which contains a resin capable of increasing the polarity bythe action of an acid and becomes more soluble in a positive developerand less soluble in a negative developer upon irradiation with anactinic ray or radiation and (ii) a negative developer (preferably anorganic developer) are required. The resist composition for negativedevelopment (i) is required to be a resist composition that forms aresist film having a receding contact angle of 70 degrees or above withrespect to water, or a resist composition that contains (A) a resincapable of increasing the polarity by the action of an acid and becomingmore soluble in a positive developer and less soluble in a negativedeveloper upon irradiation with an actinic ray or radiation, (B) acompound capable of generating an acid upon irradiation with an actinicray or radiation, (C) a solvent and (D) a resin having at least either afluorine atom or a silicon atom.

For performing the invention, it is favorable that (iii) a positivedeveloper (preferably an alkali developer) is further used.

For performing the invention, it is also favorable that (iv) an organicsolvent-containing rinse liquid for negative development is furtherused.

The resist composition for negative development as used in the inventionis a resin composition containing a resin capable of increasing itspolarity by the action of an acid and forming a film which becomes moresoluble in a positive developer and less soluble in a negative developerupon irradiation with an actinic ray or radiation. Therefore, thepresent resist composition for negative development can be used suitablyfor pattern formation through multiple development utilizing acombination of a developer (a positive developer) allowing selectivedissolution and removal of portions given exposure amounts above aspecified threshold value (a), a developer (a negative developer)allowing selective dissolution and removal of portions given exposureamounts below a differently specified threshold value (b) and a resistcomposition for negative development.

More specifically, when pattern elements on an exposure mask areprojected onto a wafer coated with a resist film by light irradiation,as shown in FIG. 3, a pattern with resolution equivalent to double thespatial frequency of the optical image (light intensity distribution)can be formed through selective dissolution and removal of regionsexposed to light of high intensities (resist portions given exposureamounts above the specified threshold value (a)) by use of a positivedeveloper and selective dissolution and removal of regions exposed tolight of low intensities (resist portions given exposure amounts belowthe specified threshold value (b)) by use of a negative developer.

When the pattern formation process using two types of developers, apositive developer and a negative developer, is carried out, thesequence of these developments has no particular restriction, and morespecifically, it is appropriate that development be carried out usingeither a positive developer or a negative developer after exposure isperformed, and then negative or positive development be carried outusing a developer different from the developer used in the firstdevelopment. And it is preferable that, after the negative development,cleaning with an organic solvent-containing rinse liquid for negativedevelopment is carried out. By the cleaning with a rinse liquidcontaining an organic solvent after negative development, moresatisfactory pattern formation becomes possible.

The pattern formation method for carrying out the invention is describedbelow in more detail.

<Method of Pattern Formation>

The present method of pattern formation preferably includes thefollowing processes, but not limited to these processes.

The processes included in the present method of pattern formation canbe:

(a) coating a substrate with a resist composition for negativedevelopment to form a resist film having a receding contact angle of 70degrees or above with respect to water, wherein the resist compositionfor negative development contains a resin capable of increasing thepolarity by the action of an acid and becomes more soluble in a positivedeveloper and less soluble in a negative developer upon irradiation withan actinic ray or radiation,

(b) exposing the resist film via an immersion medium, and

(c) performing development with a negative developer.

Alternatively, the processes included in the present method of patternformation can be:

(a′) coating a substrate with a resist composition for negativedevelopment to form a resist film, wherein the resist compositioncontains a resin capable of increasing the polarity by the action of anacid and becomes more soluble in a positive developer and less solublein a negative developer upon irradiation with an actinic ray orradiation,

(b) exposing the resist film via an immersion medium, and

(c) performing development with a negative developer

wherein

the resist composition for negative development contains:

(A) a resin capable of increasing the polarity by the action of an acidand becoming more soluble in a positive developer and less soluble in anegative developer upon irradiation with an actinic ray or radiation,

(B) a compound capable of generating an acid upon irradiation with anactinic ray or radiation,

(C) a solvent, and

(D) a resin having at least either a fluorine atom or a silicon atom

It is preferable that the present method of pattern formation furtherincludes (d) performing development with a positive developer to formresist patterns. By including this process, the pattern with resolutionequivalent to double the spatial frequency of an optical image (lightintensity distribution) can be formed.

The process (a) of coating a substrate with a resist composition fornegative development to form a resist film having a receding contactangle of 70 degrees or above with respect to water, wherein the resistcomposition for negative development contains a resin capable ofincreasing the polarity by the action of an acid and becomes moresoluble in a positive developer and less soluble in a negative developerupon irradiation with an actinic ray or radiation, or the process (a′)of coating a substrate with a resist composition for negativedevelopment to form a resist film, wherein the resist compositioncontains a resin capable of increasing the polarity by the action of anacid and becomes more soluble in a positive developer and less solublein a negative developer upon irradiation with an actinic ray orradiation may be performed using any method as long as it allows coatinga substrate with the resist composition. Examples of such a methodinclude coating methods hitherto known, such as a spin coating method, aspraying method, a roller coating method and a dip coating method. Forapplying a coating of resist composition, a spin coating method ispreferable to the others. After applying a coating of resistcomposition, the substrate is heated (pre-baked) as required. By thisheating, it becomes possible to evenly form the coating from whichundesired residual solvents are eliminated. The pre-bake temperature hasno particular limitations, but it is preferably from 50° C. to 160° C.,far preferably from 60° C. to 140° C.

The substrate on which resist film is formed has no particularrestrictions in the invention, and it is possible to use any ofinorganic substrates made from silicon, SiN, SiO₂ and the like,coating-type inorganic substrates including SOG, and substratesgenerally used in lithographic processes for production ofsemiconductors, such as ICs, and circuit boards of liquid crystaldisplays, thermal heads and the like, and photofabrication of otherdevices.

Before the resist film is formed, the substrate may be coated with anantireflective film in advance.

As the antireflective film, any of inorganic ones formed from titanium,titanium oxide, titanium nitride, chromium oxide, carbon and amorphoussilicon, respectively, and organic ones formed from, e.g., a combinationof a light absorbent and a polymeric material can be used. In addition,commercially available organic antireflective films including DUV-30series and DUV-40 series manufactured by Brewer Science Inc., AR-2, AR-3and AR-5 manufactured by Shipley Company, and ARC series, such asARC29A, manufactured by Nissan Chemical Industries, Ltd. can also beused.

The film formed on a substrate through application of a resistcomposition for negative development in the invention has a highreceding contact angle with respect to an immersion liquid.

The term “receding contact angle” as used herein refers to the contactangle measured when the contact line at a liquid droplet-substrateinterface recedes, and this contact angle is generally known to beuseful for simulation of the mobility of a liquid droplet in a dynamicstate. And the receding contact angle is defined simply as a contactangle measured under a condition that the liquid droplet interface isreceding by causing a liquid droplet discharged from a needle tip todraw back into the needle after the liquid droplet has deposited on thesubstrate surface, and can be determined by use of a contact anglemeasurement method generally referred to as the extension-contractionmethod.

In the immersion exposure process, it is required for an immersionliquid to move over a wafer so as to follow movements of an exposurehead in a state of scanning the wafer at a high speed and formingexposure patterns. Therefore, the contact angle of an immersion liquidin a dynamic state with respect to a resist film becomes important, andit is required for the resist film to have properties of avoiding liquiddroplets from remaining on the surface and allowing the immersion liquidto follow high-speed scanning of an exposure head.

To be more specific, it is preferable in the invention that the filmformed on a substrate through application of a resist composition fornegative development has a receding contact angle of 70 degrees or abovewith respect to water. By enhancing the receding contact angle, itbecomes possible to follow lens movements in immersion exposure and toform patterns of satisfactory LWR in a high throughput. In addition, italso becomes possible to ensure an even contact of a negative developerwith a wafer during development, thereby allowing prevention of scumformation by poor development.

The receding contact angle of the resist film with respect to water ispreferably from 70 degrees to 100 degrees, far preferably from 70degrees to 90 degrees, especially preferably from 75 degrees to 90degrees.

In order to form a resist film having a high receding contact angle withrespect to an immersion liquid, “resist compositions for negativedevelopment” as described below can be used. Of such compositions, Resin(D)-containing resist compositions for negative development” are used toadvantage.

When a resist composition for negative development is free of Resin (D),it is preferable that Resin (A) in the resist composition is highlyhydrophobic enough to form a film having a high receding contact anglewith respect to an immersion liquid. More specifically, it is preferableto use resins free of alkali-soluble groups (such as carboxylic acidgroups or sulfonic acid groups) other than fluorinated alcohol groups.

In the method of the invention, (i) a resist composition for negativedevelopment which contains a resin capable of increasing the polarity bythe action of an acid and becomes more soluble in a positive developerand less soluble in a negative developer and (ii) a negative developer(preferably an organic developer) are required. Of resist compositionsof such a kind, compositions usable for exposure to light of wavelengthsof 250 nm or shorter are preferred, and those usable for exposure tolight of wavelengths of 200 nm or shorter are far preferred. Examples ofsuch compositions include those containing combinations of theingredients described hereafter in the section <Resist Composition forNegative Development>.

In the process (b) exposing the resist film via an immersion medium, theexposure of a resist film to light can be carried out according to anyof generally well-known methods. The resist film is preferably exposedvia an immersion liquid to an actinic ray or radiation having passedthrough a given mask. The exposure amount, though can be chosen asappropriate, is generally adjusted to a range of 1 to 100 mJ/cm².

The present method poses no particular limitations to wavelengths of alight source used in exposure apparatus, but light with wavelengths of250 nm or shorter, especially 200 nm or shorter, is used to advantage.Examples of a light source suitable for use in the invention include aKrF excimer laser (248 nm), an ArF laser (193 nm), a F₂ excimer laser(157 nm), an EUV source (13.5 nm) and electron-beam sources. Of theselight sources, an ArF excimer laser (193 nm) is used to greateradvantage.

At the occasion of performing the immersion exposure process, a processof cleaning the film surface with an aqueous chemical may be carried out(1) after formation of the film on a substrate, and that before theexposure process, and/or (2) after the process of exposing the film tolight via an immersion liquid, and that before a process of heating thefilm.

The immersion liquid (immersion medium) used therein is preferably aliquid which is transparent to exposure light, and the refractive indexof which has the smallest possible temperature coefficient in order tominimize deformation of optical images projected onto the film. When anArF excimer laser (wavelength: 193 nm) in particular is used as a lightsource, the use of water as the immersion liquid is preferred in pointof easiness of acquisition and handling in addition to the aboveviewpoints.

When water is used, an additive (liquid) for reducing the surfacetension of water and increasing the surface activity of water may beadded in a slight proportion. This additive is preferably a liquid inwhich the resist layer on a wafer does not dissolve, and besides, whichhas negligible influence on an optical coat applied to the bottom oflens elements. And the water used is preferably distilled water.Alternatively, purified water obtained by further filtering distilledwater through an ion exchange filter may be used. By use of purifiedwater, the optical image projected onto the resist can be prevented fromsuffering deformation by impurities mixed in water.

Alternatively, a medium having a refractive index of 1.5 or above canalso be used from the viewpoint of a further increase in refractiveindex. This medium may be an aqueous solution or an organic solvent.

Between a resist film and an immersion liquid, film having poorsolubility in the immersion liquid (hereinafter referred to as“topcoat”, too) may be provided in order not to bring the resist filminto direct contact with the immersion liquid. Features required of thetopcoat are application suitability to the upper resist layer,transparency to radiation, notably 193-nm radiation, and poor solubilityin an immersion liquid. In other words, it is preferable that thetopcoat does not mingle with resist, nevertheless, it can be applied asa uniform coating to the upper resist layer.

In point of transparency to 193-nm radiation, the topcoat is preferablyformed from a polymer free of aromatic groups, and examples of such apolymer include hydrocarbon polymers, acrylate polymers, polymethacrylicacid, polyacrylic acid, polyvinyl ether, silicon-containing polymers andfluorine-containing polymers.

The topcoat may be stripped off by using a developer, or a strippingagent separately. As the stripping agent, a solvent low in permeabilityinto the resist is suitable. In point of possibility of performing thestripping-off process simultaneously with the resist developmentprocess, it is advantageous for the topcoat to be stripped off with analkali developer. From the viewpoint of stripping-off with an alkalideveloper, the topcoat is preferably acidic, while the topcoat may beneutral or alkaline in point of no intermixing with resist.

In the present method of pattern formation, an exposure process may becarried out two or more times. Although each exposure process is carriedout using far ultraviolet light, extreme ultraviolet light or anelectron beam, a different light source may be used each time, or thesame light source may be used every time. However, it is preferred thatan ArF excimer laser (wavelength: 193 nm) be used in the first exposureprocess. And the process of performing exposure via an immersion mediumcan also be repeated two or more times.

After the exposure process, (g) a heating process (referred to as bake,or PEB (post exposure bake) too) is preferably carried out, followed bydevelopment and subsequent rinse processes. Through these processes,good-quality patterns can be formed. The PEB temperature has noparticular limitations so long as good-quality resist patterns areobtained, but it is generally within the range of 40° C. to 160° C. Theheating process may be carried out two or more times.

In the invention, (c) development is carried out using a negativedeveloper, and thereby a resist pattern is formed.

When the negative development is carried out, an organic developercontaining an organic solvent is preferably used.

The organic developer usable in carrying out negative development is apolar solvent, such as a ketone solvent, an ester solvent, an alcoholsolvent, an amide solvent or an ether solvent, or a hydrocarbon solvent.Examples of a ketone solvent usable therein include 1-octanone,2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, methyl amylketone (IUPAC name: 2-heptanone), 1-hexanone, 2-hexanone, diisobutylketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethylketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone,diacetonyl alcohol, acetyl carbinol, acetophenone, methyl naphthylketone, isophorone and propylene carbonate; and examples of an estersolvent usable therein include methyl acetate, butyl acetate, ethylacetate, isopropyl acetate, amyl acetate, propylene glycol monomethylether acetate, ethylene glycol monoethyl ether acetate, diethyleneglycol monobutyl ether acetate, diethylene glycol monoethyl etheracetate, ethyl-3-ethoxypropionate, 3-methoxybutyl acetate,3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butylformate, propyl formate, ethyl lactate, butyl lactate and propyllactate.

Examples of an alcohol solvent usable therein include alcohol compounds,such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropylalcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol,isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol andn-decanol; glycol solvents, such as ethylene glycol, diethylene glycoland triethylene glycol; and glycol ether solvents, such as ethyleneglycol monomethyl ether, propylene glycol monomethyl ether, ethyleneglycol monoethyl ether, propylene glycol monoethyl ether, diethyleneglycol monomethyl ether, triethylene glycol monoethyl ether andmethoxymethyl butanol.

Examples of an ether solvent usable therein include dioxane andtetrahydrofuran in addition to the glycol ether solvents as recitedabove.

Examples of an amide solvent usable therein includeN-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide,hexamethylphosphoric triamide and 1,3-dimethyl-2-imidazol idinone.

Examples of a hydrocarbon solvent usable therein include aromatichydrocarbon solvents, such as toluene and xylene, and aliphatichydrocarbon solvents, such as pentane, hexane, octane and decane.

The solvents as recited above may be used as mixtures of two or morethereof, or as mixtures with other solvents or water.

The vapor pressure of a negative developer at 20° C. is preferably 5 kPaor below, far preferably 3 kPa or below, particularly preferably 2 kPaor below. By adjusting the vapor pressure of a negative developer to 5kPa or below, evaporation of the developer on the substrate or inside adevelopment cup can be controlled, and thereby in-plane temperatureuniformity of a wafer is improved to result in improvement of in-planedimensional uniformity of a wafer.

Examples of an organic solvent usable for a negative developer having avapor pressure of 5 kPa or below at 20° C. include ketone solvents, suchas 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, 4-heptanone, methylamyl ketone (IUPAC name: 2-heptanone), 2-hexanone, diisobutyl ketone,cyclohexanone, methylcyclohexanone, phenylacetone and methyl isobutylketone; ester solvents, such as butyl acetate, amyl acetate, propyleneglycol monomethyl ether acetate, ethylene glycol monoethyl etheracetate, diethylene glycol monobutyl ether acetate, diethylene glycolmonoethyl ether acetate, ethyl-3-ethoxypropionate, 3-methoxybutylacetate, 3-methyl-3-methoxybutyl acetate, butyl formate, propyl formate,ethyl lactate, butyl lactate and propyl lactate; alcohol solvents, suchas n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butylalcohol, tert-butyl alcohol, isobutyl alcohol, n-hexyl alcohol, n-heptylalcohol, n-octyl alcohol and n-decanol; glycol solvents, such asethylene glycol, diethylene glycol and triethylene glycol; and glycolether solvents, such as ethylene glycol monomethyl ether, propyleneglycol monomethyl ether, ethylene glycol monoethyl ether, propyleneglycol monoethyl ether, diethylene glycol monomethyl ether, triethyleneglycol monoethyl ether and methoxymethyl butanol; ether solvents, suchas tetrahydrofuran; amide solvents, such as N-methyl-2-pyrrolidone,N,N-dimethylacetamide and N,N-dimethylformamide; aromatic hydrocarbonsolvents, such as toluene and xylene; and aliphatic hydrocarbonsolvents, such as octane and decane.

Examples of an organic solvent having a vapor pressure of 2 kPa or belowat 20° C. include ketone solvents, such as 1-octanone, 2-octanone,1-nonanone, 2-nonanone, 4-heptanone, methyl amyl ketone (IUPAC name:2-heptanone), 2-hexanone, diisobutyl ketone, cyclohexanone,methylcyclohexanone and phenylacetone; ester solvents, such as butylacetate, amyl acetate, propylene glycol monomethyl ether acetate,ethylene glycol monoethyl ether acetate, diethylene glycol monobutylether acetate, diethylene glycol monoethyl ether acetate,ethyl-3-ethoxypropionate, 3-methoxybutyl acetate,3-methyl-3-methoxybutyl acetate, ethyl lactate, butyl lactate and propyllactate; alcohol solvents, such as n-butyl alcohol, sec-butyl alcohol,tert-butyl alcohol, isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol,n-octyl alcohol and n-decanol; glycol solvents, such as ethylene glycol,diethylene glycol and triethylene glycol; and glycol ether solvents,such as ethylene glycol monomethyl ether, propylene glycol monomethylether, ethylene glycol monoethyl ether, propylene glycol monoethylether, diethylene glycol monomethyl ether, triethylene glycol monoethylether and methoxymethyl butanol; amide solvents, such asN-methyl-2-pyrrolidone, N,N-dimethylacetamide and N,N-dimethylformamide;aromatic hydrocarbon solvents, such as xylene; and aliphatic hydrocarbonsolvents, such as octane and decane.

Of the negative developers as recited above, the negative developerscontaining organic solvents selected from ketone solvents, estersolvents or ether solvents are used to good advantage, the negativedevelopers containing organic solvents selected from ester solvents areused to better advantage, and the negative developers containing butylacetate are used to best advantage.

To a developer which can be used when negative development is carriedout, a surfactant can be added in an appropriate amount, if needed.

The developer has no particular restriction as to the surfactant addedthereto, so addition of, e.g., an ionic or nonionic surfactantcontaining at least one fluorine atom and/or at least one silicon atommay be made. Examples of such an ionic or nonionic surfactant includethe surfactants disclosed in JP-A-62-36663, JP-A-61-226746,JP-A-61-226745, JP-A-62-170950, JP-A-63-34540, JP-A-7-230165,JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, and U.S. Pat. Nos. 5,405,720,5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511 and5,824,451. Of these surfactants, nonionic surfactants are preferable tothe others. Though no particular restrictions are imposed on suchnonionic surfactants, it is far preferable to use a surfactantcontaining at least one fluorine atom or a surfactant containing atleast one silicon atom.

The amount of a surfactant used is generally from 0.001 to 5 mass %,preferably from 0.005 to 2 mass %, far preferably from 0.01 to 0.5 mass%, of the total amount of the developer to which the surfactant isadded.

Examples of a development method applicable herein include a method ofdipping a substrate for a predetermined period of time into a tankfilled with a developer (dip method), a method of developing by moundinga developer on a substrate surface by surface tension and leaving thedeveloper at rest for a fixed period of time (puddle method), a methodof spraying a developer on a substrate surface (spray method) and amethod of keeping on dispensing a developer onto a substrate spinning ata constant speed while scanning the substrate at a constant speed with adeveloper dispense nozzle (dynamic dispense method).

The process of performing development is preferably a process of feedinga negative developer onto the surface of a substrate while spinning thesubstrate.

After the process of negative development, a process of stopping thedevelopment while replacing the negative developer with another solventmay be carried out.

After the completion of the negative development, the present methodpreferably includes a cleaning process using an organicsolvent-containing rinse liquid for negative development.

The rinse liquid used in the rinse process after negative developmenthas no particular restrictions so long as it does not dissolve resistpatterns, and solutions containing general organic solvents can be used.More specifically, the solution suitably used as the rinse liquid is asolution containing at least one kind of organic solvent chosen fromhydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents,amide solvents or ether solvents. And it is preferable that, afternegative development, the cleaning process is carried out using a rinseliquid containing at least one kind of solvent chosen from ketonesolvents, ester solvents, alcohol solvents or amide solvents. It ispreferable by far that, after negative development, the cleaning processis carried out using a rinse liquid containing an alcohol solvent or anester solvent, and it is especially preferable that, after negativedevelopment, the cleaning process is carried out using a rinse liquidcontaining monohydric alcohol. Herein, the monohydric alcohol used inthe rinse process after the negative development may have any ofstraight-chain, branched or cyclic forms, with examples including1-butanol, 2-butanol, 3-methyl-1-butanol, tert-butyl alcohol,1-pentanol, 2-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol,2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol and 4-octanol.Of these alcohol solvents, 1-hexanol, 2-hexanol, 1-heptanol and3-methyl-1-butanol are preferred over the others.

Two or more of the ingredients recited above may be mixed together, oreach ingredient may be used as a mixture with an organic solvent otherthan the above-recited ones.

The process of cleaning with a rinse liquid containing an organicsolvent can also be carried out two or more times by using two or moredifferent rinse liquids, respectively.

The rinse liquid used in the process (e) of cleaning with a rinse liquidcontaining an organic solvent preferably contains at least one of thedeveloper incredients used in the process (c) of performing developmentwith a negative developer.

The water content in the rinse liquid is preferably 10 mass % or below,far preferably 5 mass % or below, particularly preferably 3 mass % orbelow. By controlling the water content to 10 mass % or below,satisfactory developing properties can be attained.

The vapor pressure of the rinse liquid used after negative development,as measured at 20° C., is preferably from 0.05 kPa to 5 kPa, farpreferably from 0.1 kPa to 5 kPa, especially preferably from 0.12 kPa to3 kPa. By adjusting the vapor pressure of the rinse liquid to the rangeof 0.05 kPa to 5 kPa, in-plane temperature uniformity of a wafer isenhanced, and besides, wafer swelling caused by penetration of the rinseliquid can be controlled; as a result, in-plane dimensional uniformityof a wafer can be improved.

It is also possible to use the rinse liquid to which a surfactant isadded in an appropriate amount.

In the rinse process, the wafer having undergone the negativedevelopment is subjected to cleaning treatment with the organicsolvent-containing rinse liquid. There is no particular restriction onthe method for the cleaning treatment. For example, a method of keepingon coating a substrate spinning at a constant speed with a rinse liquid(spin coating method), a method of dipping a substrate in a tank filledwith a rinse liquid (dip method) and a method of spraying a rinse liquidonto the substrate surface (spray method) can be applied thereto.

The process of cleaning with a rinse liquid containing an organicsolvent is preferably a process of feeding the rinse liquid onto thesurface of a substrate while spinning the substrate.

It is particularly preferred that the cleaning process be performed by aspin coating method and then the rinse liquid be eliminated from thesubstrate by spinning the substrate at revs ranging from 2,000 rpm to4,000 rpm.

In the present method of forming resist patterns, it is preferred that(d) a process of performing development with a positive developer befurther included.

As the positive developer, an alkali developer can be suitably used. Thedeveloper preferred as the alkali developer is a developer containing anaqueous solution of at least one amine compound selected from primaryamine compounds, secondary amine compounds, tertiary amine compounds orquaternary amine compounds. Examples of usable alkali developers includealkaline aqueous solutions of inorganic alkalis such as sodiumhydroxide, potassium hydroxide, sodium carbonate, sodium silicate,sodium metasilicate and aqueous ammonia, primary amines such asethylamine and n-propylamine, secondary amines such as diethylamine anddi-n-butylamine, tertiary amines such as triethylamine andmethyldiethylamine, alcoholamines such as dimethylethanolamine andtriethanolamine, quaternary ammonium salts such as tetramethylammoniumhydroxide and tetraethylammonium hydroxide, and cyclic amines such aspyrrole and piperidine. Of these alkaline aqueous solutions, an aqueoussolution of tetraethylammonium hydroxide is preferred over the others.

The alkali developers as recited above may also be used after alcoholcompounds and surfactants are further added thereto in appropriateamounts.

The alkali concentration of an alkali developer (the amine compoundconcentration in a developer, relative to the total mass of thedeveloper) is generally from 0.01 to 20 mass %.

The pH of an alkali developer is generally from 10.0 to 15.0.

The time to perform development with an alkali developer is generallyfrom 10 to 300 seconds.

The alkali concentration (and pH) of an alkali developer and thedevelopment time can be adjusted as appropriate in response to patternsto be formed.

After the process (d) of performing development with a positivedeveloper, it is preferred that (f) a rinse process be further included.

It is far preferred that the rinse liquid used in the rinse process (0be purified water.

It is also possible to use a rinse liquid to which an appropriate amountof surfactant is added.

Further, it is possible to carry out treatment with a supercriticalfluid after development processing or rinse processing for the purposeof eliminating the developer or the rinse liquid adhering to patterns.

Furthermore, it is possible to carry out heat treatment after thetreatment with a supercritical fluid for the purpose of eliminatingwater remaining in patterns.

Resist compositions for negative development, which are usable in theinvention, are described below.

<Resist Composition for Negative Development>

(A) Resin that can Increase Polarity by Action of Acid

The resin usable in a resist composition according to the invention andcapable of increasing the polarity by the action of an acid is a resinhaving groups capable of decomposing by the action of an acid to producealkali-soluble groups (hereinafter referred to as “acid-decomposablegroups”) in either its main chain, or side chains, or both (hereinafterreferred to as “an acid-decomposable resin”, “an acid-decomposable Resin(A)” or “a Resin (A)”), and preferably a resin having mononuclear orpolynuclear alicyclic hydrocarbon structures and capable of increasingits polarity, increasing its solubility in an alkali developer anddecreasing its solubility in an organic solvent by the action of an acid(hereinafter referred to as “an alicyclic hydrocarbon-containingacid-decomposable resin”). Reasons for those changes are not clear, butas a reason it is likely thought that the resin causes a great change inpolarity by undergoing the irradiation with an actinic ray or radiationto result in enhancement of dissolution contrasts in both the case ofdevelopment with a positive developer (preferably an alkali developer)and the case of development with a negative developer (preferably anorganic solvent). Further, it is thought that, because of highhydrophobicity of the resin having mononuclear or polynuclear aliphatichydrocarbon structures, the developability enhancement is caused in thecase where resist film regions low in irradiation intensity aredeveloped with a negative developer (preferably an organic solvent).

The present resist composition containing a resin capable of increasingits polarity by the action of an acid can be used suitably for the caseof irradiation with ArF excimer laser.

The acid-decomposable resin includes a unit having an acid-decomposablegroup.

A group suitable as the group capable of decomposing by the action of anacid (the acid-decomposable group) is a group obtained by substituting agroup capable of splitting off by the action of an acid for a hydrogenatom of an alkali-soluble group.

Examples of alkali-soluble groups include groups respectively having aphenolic hydroxyl group, a carboxylic acid group, a fluorinated alcoholgroup, a sulfonic acid group, a sulfonamido group, a sulfonylimidogroup, an (alkylsulfonyl)(alkylcarbonyl)methylene group, an(alkylsulfonyl)(alkylcarbonyl)imido group, a bis(alkylcarbonyl)methylenegroup, a bis(alkylcarbonyl)imido group, a bis(alkylsulfonyl)methylenegroup, a bis(alkylsulfonyl)imido group, a tris(alkylcarbonyl)methylenegroup and a tris(alkylsulfonyl)methylene group.

Of these alkali-soluble groups, a carboxylic acid group, a fluorinatedalcohol group (preferably a hexafluoroisopropanol group) and a sulfonicacid group are preferred over the others.

Examples of a group capable of splitting off by the action of an acidinclude groups of formula —C(R₃₆)(R₃₇)(R₃₈), groups of formula—C(R₃₆)(R₃₇)(OR₃₉), and groups of formula —C(R_(o1))(R₀₂)(OR₃₉).

In these formulae, R₃₆ to R₃₉ each represent an alkyl group, acycloalkyl group, an aryl group, an aralkyl group or an alkenyl groupindependently. R₃₆ and R₃₇ may combine with each other to form a ring.R₀₁ and R₀₂ each represent a hydrogen atom, an alkyl group, a cycloalkylgroup, an aryl group, an aralkyl group or an alkenyl groupindependently.

Examples of a group suitable as an acid decomposable group include cumylester groups, enol ester groups, acetal ester groups and tertiary alkylester groups. Of these groups, tertiary alkyl ester groups are preferredover the others.

The alicyclic hydrocarbon-containing acid-decomposable resin ispreferably a resin having at least one kind of repeating units selectedfrom repeating units having alicyclic hydrocarbon-containing partialstructures represented by any of the following formulae (pI) to (pV) orrepeating units represented by the following formula (II-AB).

In the formulae (pI) to (pV), R₁₁ represents a methyl group, an ethylgroup, an n-propyl group, an isopropyl group, an n-butyl group, anisobutyl group or a sec-butyl group, and Z represents atoms forming acycloalkyl group together with the carbon atom.

R₁₂ to R₁₆ each represent a 1-4C straight-chain or branched alkyl group,or a cycloalkyl group independently, provided that at least one of R₁₂to R₁₄, or either R₁₅ or R₁₆ represents a cycloalkyl group.

R₁₇ to R₂₁ each represent a hydrogen atom, a 1-4C straight-chain orbranched alkyl group or a cycloalkyl group independently, provided thatat least one of R₁₇ to R₂₁ represents a cycloalkyl group. In addition,either R₁₉ or R₂₁ is required to represent a 1-4C straight-chain orbranched alkyl group or a cycloalkyl group.

R₂₂ to R₂₅ each represent a hydrogen atom, a 1-4C straight-chain orbranched alkyl group or a cycloalkyl group independently, provided thatat least one of R₂₂ to R₂₅ represents a cycloalkyl group. Alternatively,R₂₃ and R₂₄ may combine with each other to form a ring.

In the formula (II-AB), R₁₁′ and R₁₂′ each represent a hydrogen atom, acyano group, a halogen atom or an alkyl group independently.

Z′ represents atoms forming an alicyclic structure together with the twobonded carbon atoms (C—C).

The formula (II-AB) is preferably the following formula (II-ABI) orformula (II-AB2).

In the formulae (II-ABI) and (II-AB2), R₁₃′ to R₁₆′ each independentlyrepresent a hydrogen atom, a halogen atom, a cyano group, —COOH, —COOR₅,a group capable of decomposing by the action of an acid,—C(═O)—X-A′—R₁₇′, an alkyl group or a cycloalkyl group. At least two ofR₁₃′ to R₁₆′ may combine with each other to form a ring.

Herein, R₅ represents an alkyl group, a cycloalkyl group or a grouphaving a lactone structure.

X represents an oxygen atom, a sulfur atom, —NH—, —NHSO₂— or —NHSO₂NH—.

A′ represents a single bond or a divalent linkage group.

R₁₇′ represents —COOH, —COOR₅, —CN, a hydroxyl group, an alkoxyl group,—CO—NH—R₆, —CO—NH—SO₂—R₆ or a group having a lactone structure.

R₆ represents an alkyl group or a cycloalkyl group.

n represents 0 or 1.

The alkyl group which R₁₂ to R₂₅ each can represent in the formulae (pI)to (pV) is preferably a 1-4C straight-chain or branched alkyl group.

The cycloalkyl group which R₁₁ to R₂₅ each can represent or thecycloalkyl group which can be formed of Z and the carbon atom may bemonocyclic or polycyclic. Examples of such a cycloalkyl group includegroups each containing at least 5 carbon atoms and having a monocyclo,bicyclo, tricyclo or tetracyclo structure. The number of carbon atoms insuch a structure is preferably from 6 to 30, particularly preferablyfrom 7 to 25. These cycloalkyl groups may have substituents.

Suitable examples of such a cycloalkyl group include an adamantyl group,a noradamantyl group, a decaline residue, a tricyclodecanyl group, atetracyclododecanyl group, a norbornyl group, a cedrol group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, a cyclodecanyl group and a cyclododecanyl group. Of these groups,an adamantyl group, a norbornyl group, a cyclohexyl group, a cyclopentylgroup, a tetracyclodecanyl group and a tricyclodecanyl group arepreferred over the others.

Each of those alkyl groups and cycloalkyl groups may further have asubstituent. Examples of such a substituent include an alkyl group(1-4C), a halogen atom, a hydroxyl group, an alkoxyl group (1-4C), acarboxyl group and an alkoxycarbonyl group (2-6C). Herein, the alkyl,alkoxy and alkoxycarbonyl groups each may further have a substituent,such as a hydroxyl group, a halogen atom or an alkoxyl group.

In the resins, the structures represented by the formulae (pI) to (pV)can be used for protection of alkali-soluble groups. Examples of suchalkali-soluble groups include various groups known in this technicalfield.

More specifically, such a protected alkali-soluble group has a structureformed by substituting the structure represented by any of the formulae(pI) to (pV) for the hydrogen atom of a carboxylic acid group, asulfonic acid group, a phenol group or a thiol group. Of thesestructures, structures formed by substituting the structures representedby formulae (pI) to (pV) for the hydrogen atoms of carboxylic acidgroups or sulfonic acid groups are preferable to the others.

As repeating units containing alkali-soluble groups protected by thestructures of formulae (pI) to (pV), repeating units represented by thefollowing formula (pA) are suitable.

In the formula (pA), each R represents a hydrogen atom, a halogen atomor a 1-4C straight-chain or branched alkyl group. Two or more Rs may bethe same or different.

A represents a single bond, an alkylene group, an ether group, athioether group, a carbonyl group, an ester group, an amido group, asulfonamido group, a urethane group, a urea group, or a combination oftwo or more of the groups recited above, preferably a single bond.

R_(p) ₁ represents any of the formulae (pI) to (pV). The most suitableof repeating units represented by the formula (pA) is a repeating unitderived from 2-alkyl-2-adamantyl (meth)acrylate ordialkyl(1-adamantyl)methyl (meth)acrylate.

Examples of the repeating unit having an acid-decomposable group areillustrated below, but these examples should not be construed aslimiting the scope of the invention.

(In the following formulae, Rx represents H, CH₃ or CH₂OH, and Rxa andRxb each represent a 1-4C alkyl group.)

Examples of a halogen atom which R₁C and R₁₂′ each can represent in theformula (II-AB) include a chlorine atom, a bromine atom, a fluorine atomand an iodine atom.

Examples of an alkyl group which R₁₁′ and R₁₂′ each can represent in theformula (II-AB) include 1-10C straight-chain or branched alkyl groups.

The atoms Z′ for forming an alicyclic structure are atoms forming anunsubstituted or substituted alicyclic hydrocarbon as a repeating unitof the resin, particularly preferably atoms forming a bridged alicyclichydrocarbon as a repeating unit.

Examples of a skeleton of the alicyclic hydrocarbon formed include thesame skeletons as the alicyclic hydrocarbon groups represented by R₁₂ toR₂₅ in the formulae (pI) to (pV) have.

The skeleton of the alicyclic hydrocarbon may have a substituent.Examples of such a substituent include the groups represented by R₁₃′ toR₁₆′ in the formula (II-AB1) or (II-AB2).

In the alicyclic hydrocarbon-containing acid-decomposable resin relatingto the invention, groups capable of decomposing by the action of an acidcan be incorporated into at least one type of repeating units chosenfrom repeating units having aliphatic hydrocarbon-containing partialstructures represented by any of the formulae (pI) to (pV), repeatingunits represented by the formula (II-AB) or repeating units ofcopolymerization components described hereinafter. However, it ispreferable that the groups capable of decomposing by the action of anacid are incorporated into repeating units having alicyclichydrocarbon-containing partial structures represented by any of theformulae (pI) to (pV).

Various kinds of substituents as R₁₃′ to R₁₆′ in the formula (II-AB1) or(II-AB2) may also become substituents of atoms Z′ for forming analicyclic hydrocarbon structure or a bridged alicyclic hydrocarbonstructure in the formula

Examples of repeating units represented by the formula (II-AB1) or(H-AB2) are illustrated below, but these examples should not beconstrued as limiting the scope of the invention.

The alicyclic hydrocarbon-containing acid-decomposable resin for use inthe invention preferably has lactone groups. As the lactone groups, anygroups can be used as long as they have lactone structures. Suitableexamples of a lactone group include groups having 5- to 7-membered ringlactone structures, preferably groups in a state that 5- to 7-memberedring lactone structures fuse with other ring structures to form bicycloor Spiro structures. It is preferable by far that the alicyclichydrocarbon-containing acid-decomposable resin for use in the inventionhas repeating units containing the groups having lactone structuresrepresented by any of the following formulae (LC1-1) to (LC1-16).Alternatively, the groups having lactone structures may be bondeddirectly to the main chain. The lactone structures used to advantage aregroups represented by the formulae (LC1-1), (LC1-4), (LC1-5), (LC1-6),(LC1-13) and (LC1-14), and the use of specified lactone structurescontributes to improvements in line edge roughness and developmentdefects.

The lactone structure moieties each may have a substituent (Rb₂) orneedn't. Suitable examples of a substituent (Rb₂) include 1-8C alkylgroups, 4-7C cycloalkyl groups, 1-8C alkoxyl groups, 1-8C alkoxycarbonylgroups, a carboxyl group, halogen atoms, a hydroxyl group, a cyano groupand acid-decomposable groups. n₂ represents an integer of 0 to 4. Whenn₂ is 2 or above, a plurality of Rb₂s may be the same or different, orthey may combine with each other to form a ring.

Examples of a repeating unit containing a group having a lactonestructure represented by any of the formulae (LC1-1) to (LC1-16) includethe repeating units represented by the formula (II-AB1) or (II-AB2)wherein at least one of R₁₃′ to R₁₆′ is a group having the lactonestructure represented by any of the formulae (LC1-1) to (LC1-16) (forinstance, R₅ in —COOR₅ represents a group having the lactone structurerepresented by any of the formulae (LC1-1) to (LC1-16)), and repeatingunits represented by the following formula (AI).

In the formula (AI), Rb₀ represents a hydrogen atom, a halogen atom or a1-4C alkyl group. Examples of a suitable substituent the alkyl group ofRb₀ may have include a hydroxyl group and halogen atoms.

Examples of a halogen atom represented by Rb₀ include a fluorine atom, achlorine atom, a bromine atom and an iodine atom.

Rb₀ is preferably a hydrogen atom, a methyl group, a hydroxymethyl groupor a trifluoromethyl group, and more preferably a hydrogen atom or amethyl group.

Ab represents a single bond, an alkylene group, a divalent linkage grouphaving a mononuclear or polynuclear alicyclic hydrocarbon structure, anether linkage, an ester linkage, a carbonyl group, or a divalent groupformed by combining two or more of the groups recited above. Thepreferred as Ab is a single bond or a linkage group represented by-Ab₁-CO₂—. Ab₁ is a straight-chain or branched alkylene group or amononuclear or polynuclear cycloalkylene group, preferably a methylenegroup, an ethylene group, a cyclohexylene group, an adamantylene groupor a norbornylene group.

V represents a group represented by any of the formulae (LC1-1) to(LC1-16).

A repeating unit having a lactone structure generally has opticalisomers, and any of the optical isomers may be used. Further, oneoptical isomer may be used by itself, or two or more of optical isomersmay be used as a mixture. When one optical isomer is mainly used, theoptical purity (ee) thereof is preferably 90 or above, far preferably 95or above.

Examples of a repeating unit containing a group having a lactonestructure are illustrated below, but these examples should not beconstrued as limiting the scope of the invention.

(In each of the following formulae, Rx is H, CH₃, CH₂OH or CF₃)

(In each of the following formulae, Rx is H, CH₃, CH₂OH or CF₃)

(In each of the following formulae, Rx is H, CH₃, CH₂OH or CF₃)

The alicyclic hydrocarbon-containing acid-decomposable resin for use inthe invention preferably has repeating units containing organic groupshaving polar groups, especially repeating units having alicyclichydrocarbon structures substituted with polar groups. By having suchrepeating units, the resin can contribute to enhancement of adhesivenessto a substrate and affinity for a developer. As the alicyclichydrocarbon part of the alicyclic hydrocarbon structure substituted witha polar group, an adamantyl group, a diamantyl group or a norbornylgroup is suitable. As the polar group in such a structure, a hydroxylgroup or a cyano group is suitable. As the alicyclic hydrocarbonstructures substituted with polar groups, partial structures representedby the following formulae (VIIa) to (VIId) are suitable.

In the formulae (VIIa) to (VIIc), R_(2C) to R_(4C) each represent ahydrogen atom, a hydroxyl group or a cyano group independently, providedthat at least one of them represents a hydroxyl group or a cyan group.In such partial structures, it is preferable that one of R_(2C) toR_(4C) is a hydroxyl group and the remainder are hydrogen atoms, andthat two of R_(2C) to R_(4C) are hydroxyl groups and the remainder is ahydrogen atom.

In the partial structure of formula (VIIa), the case where two of R_(2C)to R_(4C) are hydroxyl groups and the remainder is a hydrogen atom isfar preferred.

Examples of repeating units containing groups represented by theformulae (VIIa) to (VIId) include the repeating units represented by theformula (II-AB1) or (II-AB2) wherein at least one of R₁₃′ to R₁₆′ is agroup represented by any of the formulae (VIIa) to (VIId) (for example,R₅ in —COOR₅ represents a group represented by any of the formulae(VIIa) to (VIId)), and repeating units represented by the followingformulae (AIIa) to (AIId).

In the formula (AIIa) to (AIId), R₁c represents a hydrogen atom, amethyl group, a trifluoromethyl group or a hydroxymethyl group, and R₂cto R₄c have the same meanings as in the formulae (VIIa) to (VIIe).

Examples of repeating units represented by the formulae (AIIa) to (AIId)are illustrated below, but these examples should not be construed aslimiting the scope of the invention.

The alicyclic hydrocarbon-containing acid-decomposable resin for use inthe invention may have repeating units represented by the followingformula (VIII).

In the formula (VIII), Z₂ represents —O— or —N(R₄₁)—. R₄₁ represents ahydrogen atom, a hydroxyl group, an alkyl group or —OSO₂—R₄₂. R₄₂represents an alkyl group, a cycloalkyl group or a camphor residue. Thealkyl groups of R₄₁ and R₄₂ may be substituted with halogen atoms(preferably fluorine atoms) or so on.

Examples of a repeating unit represented by the formula (VIII) areillustrated below, but these examples should not be construed aslimiting the scope of the invention.

The alicyclic hydrocarbon-containing acid-decomposable resin for use inthe invention preferably has repeating units containing alkali-solublegroups, and far preferably has repeating units containing carboxylgroups. The presence of such groups in the repeating units can enhanceresolution in the use for contact hole. Suitable examples of a repeatingunit containing a carboxyl group include a repeating unit containing thecarboxyl group bonded directly to the main chain of resin, such as arepeating unit derived from acrylic acid or methacrylic acid, arepeating unit containing the carboxyl group attached to the main chainof resin via a linkage group, and a unit introduced as a polymer chainterminal by using a polymerization initiator or chain transfer agenthaving an alkali-soluble group at the time of polymerization. Therein,the linkage group may have a mononuclear or polynuclear cyclichydrocarbon structure. Of these repeating units, those derived fromacrylic acid and methacrylic acid in particular are preferred.

The alicyclic hydrocarbon-containing acid-decomposable resin for use inthe invention may further have repeating units which each contain 1 to 3groups represented by the following formula (F1). The presence of thesegroups contributes to improvement in line edge roughness quality.

In the formula (F1), R₅₀ to R₅₅ each represent a hydrogen atom, afluorine atom or an alkyl group independently, provided that at leastone of R₅₀ to R₅₅ is a fluorine atom or an alkyl group at least onehydrogen atom of which is substituted with a fluorine atom.

Rx represent a hydrogen atom or an organic group (preferably anacid-decomposable blocking group, an alkyl group, a cycloalkyl group, anacyl group or an alkoxycarbonyl group).

The alkyl group represented by R₅₀ to R₅₅ each may be substituted with ahalogen atom such as a fluorine atom, a cyano group or so on, andsuitable examples thereof include 1-3C alkyl groups, such as a methylgroup and a trifluoromethyl group.

Nevertheless, it is preferable that all of R₅₀ to R₅₅ are fluorineatoms. Suitable examples of an organic group represented by Rx includeacid-decomposable blocking groups, and alkyl, cycloalkyl, acyl,alkylcarbonyl, alkoxycarbonyl, alkoxycarbonylmethyl, alkoxymethyl and1-alkoxyethyl groups which each may have a substituent.

The repeating units containing groups represented by the formula (F1)are preferably repeating units represented by the following formula(F2).

In the formula (F2), Rx represents a hydrogen atom, a halogen atom, or a1-4C alkyl group. The substituent the alkyl group of Rx may have ispreferably a hydroxyl group or a halogen atom.

Fa represents a single bond, or a straight-chain or branched alkylenegroup (preferably a single bond).

Fb represents a mononuclear or polynuclear cyclic hydrocarbon group.

Fc represents a single bond, or a straight-chain or branched alkylenegroup (preferably a single bond or a methylene group).

F1 represents a group represented by the formula (F1).

P1 represents 1, 2 or 3.

The cyclic hydrocarbon group of Fb is preferably a cyclopentylene group,a cyclohexylene group or a norbornylene group.

Examples of the repeating unit having a group represented by the formula(F1) are illustrated below, but these examples should not be construedas limiting the scope of the invention.

The alicyclic hydrocarbon-containing acid-decomposable resin for use inthe invention may further contain repeating units having alicyclichydrocarbon structures and not showing acid decomposability. By thepresence of such repeating units, elution of low molecular componentsfrom a resist coating into an immersion liquid during the performance ofimmersion lithography can be reduced. Examples of such repeating unitsinclude those derived from 1-adamantyl (meth)acrylate, tricyclodecanyl(meth)acrylate and cyclohexayl (meth)acrylate.

Examples of the repeating units having alicyclic hydrocarbon structuresand not showing acid decomposability include repeating units containingneither a hydroxy group nor a cyano group, and are preferably repeatingunits represented by the following formula (IX).

In the formula (IX), R₅ represents a hydrocarbon group having at leastone cyclic structure and containing neither a hydroxyl group nor a cyanogroup.

Ra represents a hydrogen atom, an alkyl group or —CH₂—O—Ra₂. Herein, Ra₂represents a hydrogen atom, an alkyl group or an acyl group. Ra ispreferably a hydrogen atom, a methyl group, a hydroxymethyl group or atrifluoromethyl group, and more preferably a hydrogen atom or a methylgroup.

The cyclic structure contained in R₅ may be a monocyclic hydrocarbongroup or a polycyclic hydrocarbon group. Examples of the monocyclichydrocarbon group include 3-12C cycloalkyl groups such as a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group and a cyclooctyl group,and 3-12C cycloalkenyl groups such as a cyclohexenyl group. Of thesemonocyclic hydrocarbon groups, 3-7C monocyclic hydrocarbon groups,especially a cyclopentyl group and a cyclohexyl group, are preferredover the others.

The polycyclic hydrocarbon group may be an assembled-ring hydrocarbongroup or a bridged-ring hydrocarbon group. Examples of theassembled-ring hydrocarbon group include a bicyclohexyl group and aperhydronaphthalenyl group. Examples of the bridged hydrocarbon ringinclude bicyclic hydrocarbon rings such as a pinane ring, a bornanering, a norpinane ring, a norbornane ring and bicyclooctane rings (e.g.,a bicyclo[2.2.2]octane ring, a bicyclo[3.2.1]octane ring), tricyclichydrocarbon rings such as a homobredane ring, an adamantane ring, atricyclo[5.2.1.0^(2,6)]decane ring and a tricyclo[4.3.1.1²⁵]undecanering, and tetracyclic hydrocarbon rings such as atetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecane ring and aperhydro-1,4-methano-5,8-methanonaphthalene ring. And additionalexamples of the bridged hydrocarbon ring include condensed hydrocarbonrings formed by fusing together two or more of 5- to 8-memberedcycloalkane rings such as perhydronaphthalene (decaline),perhydroanthracene, perhydrophenanthrene, perhydroacenaphthene,perhydrofluorene, perhydroindene and perhydrophenalene rings.

Examples of a bridged-ring hydrocarbon group suitable as the cyclicstructure of R₅ include a norbornyl group, an adamantyl group, abicyclooctanyl group and a tricyclo[5.2.1.0^(2,6)]decanyl group. Ofthese groups, a norbornyl group and an adamantyl group are preferredover the others.

Each of the alicyclic hydrocarbon groups recited above may have asubstituent. Examples of a substituent suitable for those groups eachinclude a halogen atom, an alkyl group, a hydroxyl group protected by aprotective group, and an amino group protected by a protective group.Suitable examples of the halogen atom include bromine, chlorine andfluorine atoms. Suitable examples of the alkyl group include methyl,ethyl, butyl and t-butyl groups. These alkyl groups each may furtherhave a substituent. Examples of the substituent include a halogen atom,an alkyl group, a hydroxyl group protected by a protective group and anamino group protected by a protective group.

Examples of such protective groups include an alkyl group, a cycloalkylgroup, an aralkyl group, a substituted methyl group, a substituted ethylgroup, an acyl group, an alkoxycarbonyl group and an aralkyloxycarbonylgroup. Suitable examples of the alkyl group include 1-4C alkyl groups,those of the substituted methyl group include methoxymethyl,methoxythiomethyl, benzyloxymethyl, t-butoxymethyl and2-methoxyethoxymethyl groups, those of the substituted ethyl groupinclude 1-ethoxyethyl and 1-methyl-1-methoxyethyl groups, those of theacyl group include 1-6C aliphatic acyl groups such as formyl, acetyl,propionyl, butyryl, isobutyryl, valeryl and pivaloyl groups, and thoseof the alkoxycarbonyl group include 1-4C alkoxycarbonyl groups.

The proportion of repeating units represented by the formula (IX), whichhave neither a hydroxyl group nor a cyano group is preferably from 0 to40 mole %, far preferably from 0 to 20 mole %, with respect to the totalrepeating units of the alicyclic hydrocarbon-containingacid-decomposable resin.

Examples of a repeating unit represented by the formula (IX) areillustrated below, but these examples should not be construed aslimiting the scope of the invention.

In the following structural formulae, Ra represents H, CH₃, CH₂OH orCF₃.

In addition to the repeating structural units recited above, thealicyclic hydrocarbon-containing acid-decomposable resin for use in theinvention can contain a wide variety of repeating structural units forthe purpose of controlling dry etching resistance, suitability forstandard developers, adhesiveness to substrates, resist profile, andbesides, characteristics generally required for resist, such asresolution, heat resistance and sensitivity.

Examples of such repeating structural units include repeating structuralunits corresponding to the monomers as recited below, but these examplesshould not be construed as limiting the scope of the invention.

By having those repeating units, it becomes possible to make fineadjustments to properties required for the alicyclichydrocarbon-containing acid-decomposable resin, especially propertiesincluding:

(1) solubility in a coating solvent,(2) film formability (glass transition temperature),(3) solubility in a positive developer and solubility in a negativedeveloper,(4) thinning of film (hydrophilic-hydrophobic balance, alkali-solublegroup selection),(5) adhesion of unexposed areas to a substrate, and(6) dry etching resistance.

Examples of monomers suitable for the foregoing purposes includecompounds which each have one addition-polymerizable unsaturated bondand are selected from acrylic acid esters, methacrylic acid esters,acrylamides, methacrylamides, allyl compounds, vinyl ethers, or vinylesters.

In addition to those monomers, any other monomers may be copolymerizedso long as they are addition-polymerizable unsaturated compounds capableof forming copolymers together with monomers corresponding to thevarious repeating structural units mentioned above.

The ratio between mole contents of repeating structural units in thealicyclic hydrocarbon-containing acid-decomposable resin can be chosenappropriately for adjusting dry etching resistance, standard developersuitability, adhesion to substrates, resist profile, and characteristicsgenerally required for resist, such as resolution, heat resistance andsensitivity.

Examples of a preferred state of the alicyclic hydrocarbon-containingacid-decomposable resin for use in the invention include the following.

(1) A state of containing repeating units each having an alicyclichydrocarbon-containing partial structure represented by any of theformulae (pI) to (pV) (side-chain type).

Herein, the repeating units contained are preferably (meth)acrylaterepeating units each having a structure containing any of (pI) to (pV).

(2) A state of containing repeating units represented by the formula(II-AB) (main-chain type). However, the state (2) further includes thefollowing.

(3) A state of having repeating units represented by the formula(II-AB), maleic anhydride derivative and (meth)acrylate structures(hybrid type).

The content of repeating units having acid-decomposable groups in thealicyclic hydrocarbon-containing acid-decomposable resin is preferablyfrom 10 to 60 mole %, far preferably from 20 to 50 mole %, furtherpreferably from 25 to 40 mole %, of the total repeating structuralunits.

The content of repeating units having acid-decomposable groups in anacid-decomposable resin is preferably from 10 to 60 mole %, farpreferably from 20 to 50 mole %, further preferably from 25 to 40 mole%, of the total repeating structural units.

The content of repeating units having alicyclic hydrocarbon-containingpartial structures represented by the formulae (pI) to (pV) in thealicyclic hydrocarbon-containing acid-decomposable resin is preferablyfrom 20 to 70 mole %, far preferably from 20 to 50 mole %, furtherpreferably from 25 to 40 mole %, of the total repeating structuralunits.

The content of repeating units represented by the formula (II-AB) in thealicyclic hydrocarbon-containing acid-decomposable resin is preferablyfrom 10 to 60 mole %, far preferably from 15 to 55 mole %, furtherpreferably from 20 to 50 mole %, of the total repeating structuralunits.

The content of repeating units having lactone rings in anacid-decomposable resin is preferably from 10 to 70 mole %, farpreferably from 20 to 60 mole %, further preferably from 25 to 40 mole%, of the total repeating structural units.

The content of repeating units containing organic groups having polargroups in an acid-decomposable resin is preferably from 1 to 40 mole %,far preferably from 5 to 30 mole %, further preferably from 5 to 20 mole%, of the total repeating structural units.

In the resin for use in the invention, the content of repeatingstructural units based on monomers as additional copolymerizingcomponents can also be chosen appropriately according to the intendedresist performance. In general, the proportion of such repeatingstructural units is preferably 99 mole % or below, far preferably 90mole % or below, further preferably 80 mole % or below, based on thetotal mole number of the repeating structural units having alicyclichydrocarbon-containing partial structures represented by the formulae(pI) to (pV) and the repeating units represented by the formula (II-AB).

When the present resist composition for negative development is designedfor ArF exposure use, it is advantageous for the resin used therein tohave no aromatic group in point of transparency to ArF light.

As to the alicyclic hydrocarbon-containing acid-decomposable resin foruse in the invention, it is preferable that (meth)acrylate repeatingunits constitute all the repeating units of the resin. Herein, all therepeating units may be either acrylate repeating units, or methacrylaterepeating units, or mixed acrylate-and-methacrylate repeating units.However, it is preferable that the acrylate repeating units is at most50 mole % of the total repeating units.

The alicyclic hydrocarbon-containing acid-decomposable resin ispreferably a copolymer having (meth)acrylate repeating units of threetypes: a type of having at least a lactone ring, a type of having anorganic group substituted with at least either hydroxyl or cyano group,and a type of having an acid-decomposable group.

The alicyclic hydrocarbon-containing acid-decomposable resin is farpreferably a ternary copolymer containing 20-50 mole % of repeatingunits having alicyclic hydrocarbon-containing partial structuresrepresented by any of the formulae (pI) to (pV), 20-50 mole % ofrepeating units having lactone structures and 5-30 mole % of repeatingunits having alicyclic hydrocarbon structures substituted with polargroups, or a quaternary copolymer further containing 0-20 mole % ofother repeating units.

The resin preferred in particular is a ternary copolymer containing20-50 mole % of repeating units containing acid-decomposable groups,which are represented by any of the following formulae (ARA-1) to(ARA-7), 20-50 mole % of repeating units containing lactone groups,which are represented by any of the following formulae (ARL-1) to(ARL-7), and 5-30 mole % of repeating units having alicyclic hydrocarbonstructures substituted with polar groups, which are represented by anyof the following formulae (ARH-1) to (ARH-3), or a quaternary copolymerfurther containing 5-20 mole % of repeating units having carboxyl groupsor structures represented by the formula (F1), or repeating units havingalicyclic hydrocarbon structures but not showing acid decomposability.

In the following formulae, R_(xy1) represents a hydrogen atom or amethyl group, R_(xa1) and R_(xb1) each represent a methyl group or anethyl group independently, and R_(xc1) represents a hydrogen atom or amethyl group.

In the following formulae, R_(xy1) represents a hydrogen atom or amethyl group, R_(xd1) represents a hydrogen atom or a methyl group, andR_(xe1) represents a trifluoromethyl group, a hydroxyl group or a cyanogroup.

In the following formulae, R_(xy1) represents a hydrogen atom or amethyl group.

The alicyclic hydrocarbon-containing acid-decomposable resin for use inthe invention can be synthesized according to general methods (e.g.,radical polymerization). As examples of a general synthesis method,there are known a batch polymerization method in which polymerization iscarried out by dissolving monomer species and an initiator in a solventand heating them, and a drop polymerization method in which a solutioncontaining monomer species and an initiator is added dropwise to aheated solvent over 1 to 10 hours. However, it is preferred that thedrop polymerization method be used. Examples of a solvent usable in thepolymerization reaction include ethers, such as tetrahydrofuran,1,4-dioxane and diisopropyl ether; ketones, such as methyl ethyl ketoneand methyl isobutyl ketone; ester solvents, such as ethyl acetate; amidesolvents, such as dimethylformamide and dimethylacetamide; and solventsdescribed hereafter which can dissolve the present composition, such aspropylene glycol monomethyl ether acetate, propylene glycol monomethylether and cyclohexanone. It is preferable that the polymerization iscarried out using the same solvent as used for the present resistcomposition. By doing so, it becomes possible to prevent particles fromdeveloping during storage.

The polymerization reaction is preferably carried out in an atmosphereof inert gas, such as nitrogen or argon. And the polymerization isinitiated using a commercially available radical initiator (e.g., anazo-type initiator or peroxide) as polymerization initiator. The radicalinitiator is preferably an azo-type initiator, and more specifically, anazo-type initiator having an ester group, a cyano group or a carboxylgroup. Examples of such a preferred azo-type initiator includeazobisisobutyronitrile, azobisdimethylvaleronitrile and dimethyl2,2′-azobis(2-methylpropionate). An addition of such an initiator may bemade in the course of polymerization or such an initiator may be addedin several portions, if desired. After the conclusion of the reaction,the reaction solution is poured into a solvent, and the intended polymeris collected as a powder or a solid. The concentration of reactingspecies is from 5 to 50 mass %, preferably from 10 to 30 mass %, and thereaction temperature is generally from 10° C. to 150° C., preferablyfrom 30° C. to 120° C., far preferably from 60° C. to 100° C.

The polymer thus synthesized can be purified by the same method asapplicable in the case of Resin (D) described hereinafter. For thepurification, a usual method is applicable, and examples thereof includea liquid-liquid extraction method in which residual monomers andoligomeric components are eliminated by washing with water or bycombined use of appropriate solvents, a method of performingpurification in a solution state, such as an ultrafiltration method inwhich only components of molecular weight lower than a specific valueare extracted and eliminated, a reprecipitation method in which a resinsolution is dripped into a poor solvent to result in coagulation of theresin and elimination of residual monomers and so on, and a method ofperforming purification in a solid state, such as a method of washingfiltered resin slurry with a poor solvent.

As to the resin relating to the invention, the weight average molecularweight thereof is preferably from 1,000 to 200,000, far preferably from1,000 to 20,000, particularly preferably from 1,000 to 15,000, asmeasured by GPC and calculated in terms of polystyrene. By adjusting theweight average molecular weight to fall within the range of 1,000 to200,000, declines in heat resistance and dry etching resistance can beprevented, and besides, degradation in developability and filmformability deterioration from an increased viscosity can be prevented.

The polydispersity (molecular weight distribution) of the resin used isgenerally from 1 to 5, preferably from 1 to 3, far preferably from 1.2to 3.0, particularly preferably from 1.2 to 2.0. When the polydispersityis smaller, the resist pattern formed is the more excellent inresolution and resist profile, and besides, it has the smoother sidewall and the better roughness quality.

The total amount of resins relating to the invention, which are mixed inthe present resist composition, is from 50 to 99.9 mass %, preferablyfrom 60 to 99.0 mass %, of the total solids in the resist composition.

In the invention, one kind of resin may be used, or two or more kinds ofresins may be used in combination.

When the resist composition for negative development according to theinvention contains Resin (D) described hereinafter, it is preferablethat the alicyclic hydrocarbon-containing acid-decomposable Resin (A)contains neither fluorine atom nor silicon atom in point ofcompatibility with the Resin (D).

(B) Compound that can Generate Acid upon Irradiation with Actinic Ray orRadiation

The resist composition according to the invention contains a compoundcapable of generating an acid upon exposure to an actinic ray orradiation (which is also referred to as “a photo-acid generator” or“Component (B)”).

The compound usable as such a photo-acid generator can be selectedappropriately from photo-initiators for cationic photopolymerization,photo-initiators for radical photopolymerization, photodecoloring agentsfor dyes, photodiscoloring agents, compounds used in microresists andknown to generate acids upon exposure to an actinic ray or radiation, ormixtures of two or more thereof.

Examples of such compounds include diazonium salts, phosphonium salts,sulfonium salts, iodonium salts, imide sulfonate, oxime sulfonate,diazodisulfone, disulfone and o-nitrobenzylsulfonate.

In addition, polymeric compounds having such groups or compounds as togenerate acids upon exposure to an actinic ray or radiation in a stateof being introduced in their main or side chains can also be used.Examples of those polymeric compounds include the compounds as disclosedin U.S. Pat. No. 3,849,137, German Patent No. 3914407, JP-A-63-26653,JP-A-55-164824, JP-A-62-69263, JP-A-63-146038, JP-A-63-163452,JP-A-62-153853 and JP-A-63-146029.

Further, the compounds capable of generating acids by the action oflight as disclosed in U.S. Pat. No. 3,779,778 and European Patent No.126,712 can be used too.

Of the compounds capable of decomposing upon irradiation with an actinicray or radiation to generate acids, compounds represented by thefollowing formulae (ZI), (ZII) and (ZIII) respectively are preferable.

In the formula (ZI), R₂₀₁, R₂₀₂ and R₂₀₃ each represent an organic groupindependently.

X⁻ represents a non-nucleophilic anion, preferably a sulfonic acidanion, a carboxylic acid anion, a bis(alkylsulfonyl)amide anion, atris(alkylsulfonyl)methide anion, BF₄ ⁻, PF₆ ⁻ or SbF₆ ⁻, far preferablya carbon-containing organic anion.

Examples of an organic anion preferred as X⁻ include organic anionsrepresented by the following formulae.

In the above formulae, Rc₁ represents an organic group.

Examples of the organic group as Rc₁ include groups containing 1 to 30carbon atoms, preferably alkyl groups and aryl groups, which each may besubstituted, and groups formed by connecting two or more of those groupsvia one or more of linkage groups, such as a single bond, —O—, —CO₂—,—S—, —SO₃— and —SO₂N(Rd₁)—. Rd₁ represents a hydrogen atom or an alkylgroup.

Rc₃, Rc₄ and Rc₅ each represent an organic group independently. Examplesof organic groups preferred as Rc₃, Rc₄ and Rc₅ include the same organicgroups as the preferred of Rc₁, especially 1-4C perfluoroalkyl groups.

Rc₃ and Rc₄ may combine with each other to form a ring. The group formedby combining Rc₃ with Rc₄ is an alkylene group or an arylene group,preferably a 2-4C perfluoroalkylene group.

The organic groups particularly preferred as Rc₁, Rc₃, R_(c4) and Rc₅each are alkyl groups substituted with fluorine atoms or fluoroalkylgroups at their respective 1-positions and phenyl groups substitutedwith fluorine atoms or fluoroalkyl groups. By containing a fluorine atomor a fluoroalkyl group, the acid generated by irradiation with light canhave high acidity to result in enhancement of the sensitivity. Likewise,the ring formation by combination of Rc₃ and Rc₄ allows an acidityincrease of the acid generated by irradiation with light to result inenhancement of the sensitivity.

The number of carbon atoms in the organic group as R₂₀₁, R₂₀₂ and R₂₀₃each is generally from 1 to 30, preferably from 1 to 20.

Two of R₂₀₁ to R₂₀₃ may combine with each other to form a ringstructure, and the ring formed may contain an oxygen atom, a sulfuratom, an ester linkage, an amide linkage or a carbonyl group. Examplesof a group formed by combining two of R₂₀₁, R₂₀₂ and R₂₀₃ includealkylene groups (such as a butylene group and a pentylene group).

Examples of organic groups as R₂₀₁, R₂₀₂ and R₂₀₃ include theircorresponding groups in compounds (ZI-1), (ZI-2) and (ZI-3) illustratedbelow.

Additionally, the photo-acid generator may be a compound having two ormore of structures represented by formula (ZI). For instance, thephoto-acid generator may be a compound having a structure that at leastone of R₂₀₁, R₂₀₂ and R₂₀₃ in one compound represented by formula (ZI)is united with at least one of R₂₀₁, R₂₀₂ and R₂₀₃ in another compoundrepresented by formula (ZI).

Far preferred examples of a compound (ZI) include compounds (ZI-1),(ZI-2) and (ZI-3) explained blow.

The compound (ZI-1) is an arylsulfonium compound represented by theformula (ZI) wherein at least one of R₂₀₁ to R₂₀₃ is an aryl group,namely a compound having an arylsulfonium as its cation.

In such an arylsulfonium compound, all of R₂₀₁ to R₂₀₃ may be arylgroups, or one or two of R₂₀₁ to R₂₀₃ may be aryl groups and theremainder may be an alkyl group or a cycloalkyl group.

Examples of such an arylsulfonium compound include a triarylsulfoniumcompound, a diarylalkylsulfonium compound, an aryldialkylsulfoniumcompound, a diarylcycloalkylsulfonium compound and anaryldicycloalkylsulfonium compound.

The aryl group in the arylsulfonium compound is preferably an arylgroup, such as a phenyl group or a naphthyl group, or a hetroaryl group,such as an indole residue or a pyrrole residue, far preferably a phenylgroup or an indole residue. When the arylsulfonium compound has two ormore aryl groups, the two or more aryl groups may be the same ordifferent.

One or two alkyl groups which the arylsulfonium compound has as requiredare preferably 1-15C straight-chain or branched alkyl groups, withexamples including a methyl group, an ethyl group, a propyl group, ann-butyl group, a sec-butyl group and a t-butyl group.

One or two cycloalkyl groups which the arylsulfonium compound has asrequired are preferably 3-15C cycloalkyl groups, with examples includinga cyclopropyl group, a cyclobutyl group and a cyclohexyl group.

The aryl group, the alkyl group or the cycloalkyl group represented byany of R₂₀₁ to R₂₀₃ may have as a substituent an alkyl group(containing, e.g., 1 to 15 carbon atoms), a cycloalkyl group(containing, e.g., 3 to 15 carbon atoms), an aryl group (containing,e.g., 6 to 14 carbon atoms), an alkoxyl group (containing, e.g., 1 to 15carbon atoms), a halogen atom, a hydroxyl group or a phenylthio group.Suitable examples of such substituents include 1-12C straight-chain orbranched alkyl groups, 3-12C cycloalkyl groups and 1-12C straight-chain,branched or cyclic alkoxyl groups. Of these substituents, 1-4C alkylgroups and 1-4C alkoxyl groups are preferred over the others. One ofR₂₀₁ to R₂₀₃ may have such a substituent, or all of R₂₀₁ to R₂₀₃ mayhave such substituents. When R₂₀₁ to R₂₀₃ are aryl groups, it ispreferable that such a substituent is situated in the p-position of eacharyl group.

Then, the compound (ZI-2) is explained below.

The compound (ZI-2) is a compound represented by the formula (ZI) inwhich R₂₀₁ to R₂₀₃ each independently represent an organic group havingno aromatic ring. The term “aromatic ring” as used herein is intended toalso include aromatic rings containing hetero atoms.

The number of carbon atoms in an aromatic ring-free organic group aseach of R₂₀₁ to R₂₀₃ is generally from 1 to 30, preferably from 1 to 20.

Each of R₂₀₁ to R₂₀₂ is preferably an alkyl group, a cycloalkyl group,an allyl group or a vinyl group, far preferably a straight-chain,branched or cyclic 2-oxoalkyl group, or an alkoxycarbonylmethyl group,particularly preferably a straight-chain or branched 2-oxoalkyl group.

The alkyl group as each of R₂₀₁ to R₂₀₃ may have either a straight-chainor branched form, and it is preferably a 1-10C straight-chain orbranched group (e.g., a methyl group, an ethyl group, a propyl group, abutyl group, a pentyl group). The alkyl group as each of R₂₀₁ to R₂₀₃ isfar preferably a straight-chain or branched 2-oxoalkyl group, or analkoxycarbonylmethyl group.

The cycloalkyl group as each of R₂₀₁ to R₂₀₃ is preferably a 3-10Ccycloalkyl group (e.g., a cyclopentyl group, a cyclohexyl group, anorbornyl group). The cycloalkyl group as each of R₂₀₁ to R₂₀₃ is farpreferably a cyclic 2-oxoalkyl group.

Examples of a straight-chain, branched or cyclic 2-oxoalkyl groupsuitable as each of R₂₀₁ to R₂₀₃ include the groups having >C═O in the2-positions of the alkyl or cycloalkyl groups recited above.

The alkoxy moiety in an alkoxycarbonylmethyl group as each of R₂₀₁ toR₂₀₃ is preferably a 1-5C alkoxyl group (such as a methoxy, ethoxy,propoxy, butoxy or pentoxy group).

Each of groups represented by R₂₀₁ to R₂₀₃ may further be substitutedwith a halogen atom, an alkoxyl group (containing, e.g., 1 to 5 carbonatoms), a hydroxyl group, a cyano group or a nitro group.

The compound (ZI-3) is a compound represented by the following formula(ZI-3), namely a compound having a phenacylsulfonium salt structure.

In the formula (ZI-3), R_(1c) to R_(5c) each represent a hydrogen atom,an alkyl group, a cycloalkyl group, an alkoxyl group or a halogen atomindependently.

R_(6c) and R_(7c) each represent a hydrogen atom, an alkyl group or acycloalkyl group independently.

R_(x) and R_(y) each represent an alkyl group, a cycloalkyl group, anallyl group or a vinyl group independently.

Any two or more of R_(1c) to R_(7c) may combine with one another to forma ring structure, and R_(x) and R_(y) may also combine with each otherto form a ring structure. In such a ring structure, an oxygen atom, asulfur atom, an ester linkage or an amide linkage may be contained. Thegroup formed by combining any two or more of R_(1c) to R_(7c) or bycombining R_(x) and R_(y) may be a butylene group or a pentylene group.

X⁻ represents a non-nucleophilic anion, and examples thereof include thesame non-nucleophilic anions as examples of X⁻in formula (ZI) include.

The alkyl group as each of R_(1c) to R_(7c) may have either astraight-chain form or a branched form, and suitable examples thereofinclude 1-20C straight-chain or branched alkyl groups, preferably 1-12Cstraight-chain or branched alkyl groups (e.g., a methyl group, an ethylgroup, a straight-chain or branched propyl group, straight-chain orbranched butyl groups, straight-chain or branched pentyl groups).

Suitable examples of the cycloalkyl group as each of R_(1c) to R_(7c)include 3-8C cycloalkyl groups (e.g., a cyclopentyl group, a cyclohexylgroup).

The alkoxyl group as each of R_(1c) to R_(5c) may have either astraight-chain form, or a branched form, or a cyclic form, and examplesthereof include 1-10C alkoxyl groups, preferably 1-5C straight-chain andbranched alkoxyl groups (e.g., a methoxy group, an ethoxy group, astraight-chain or branched propoxy group, straight-chain or branchedbutoxy groups, straight-chain or branched pentoxy groups) and 3-8Ccycloalkoxyl groups (e.g., a cyclopentyloxy group, a cyclohexyloxygroup).

It is preferable that any of R_(1c) to R_(5c) is a straight-chain orbranched alkyl group, a cycloalkyl group, or a straight-chain, branchedor cyclic alkoxyl group, and it is far preferable that the number oftotal carbon atoms in R_(1c) to R_(5c) is from 2 to 15. By meeting theserequirements, the solvent solubility can be enhanced, and development ofparticles during storage can be prevented.

Examples of the alkyl group as each of R_(x) and R_(y) include the samegroups as examples of the alkyl group as each of R_(1c) to R_(7c)include, preferably straight-chain and branched 2-oxoakyl groups andalkoxycarbonylmethyl groups.

Examples of the cycloalkyl group as each of R_(x) and R_(y) include thesame groups as examples of the cycloalkyl group as each of R_(1c) toR_(7c) include, preferably cyclic 2-oxoakyl groups.

Examples of the straight-chain, branched and cyclic 2-oxoalkyl groupsinclude the groups having >C═O at the 2-positions of the alkyl orcycloalkyl groups as R_(1c) to R_(1c).

Examples of the alkoxy moiety in the alkoxycarbonylmethyl group includesthe same alkoxyl groups as R_(1c) to R₅ each may represent.

Each of R_(x) and R_(y) is preferably an alkyl group containing at least4 carbon atoms, far preferably an alkyl group containing at least 6carbon atoms, further preferably an alkyl group containing at least 8carbon atoms.

In the formulae (ZII) and (ZIII), R₂₀₄ to R₂₀₇ each represent an arylgroup, an alkyl group or a cycloalkyl group independently.

The aryl group as each of R₂₀₄ to R₂₀₇ is preferably a phenyl group or anaphthyl group, far preferably a phenyl group.

The alkyl group as each of R₂₀₄ to R₂₀₇ may have either a straight-chainform or a branched form, with suitable examples including 1-10Cstraight-chain and branched alkyl groups (e.g., a methyl group, an ethylgroup, a propyl group, a butyl group, a pentyl group).

The cycloalkyl group as each of R₂₀₄ to R₂₀₇ is preferably a 3-10Ccycloalkyl group (e.g., a cyclopentyl group, a cyclohexyl group, anorbornyl group).

The groups represented by R₂₀₄ to R₂₀₇ may have substituents. Examplesof such substituents include alkyl groups (e.g., those containing 1 to15 carbon atoms), cycloalkyl groups (e.g., those containing 3 to 15carbon atoms), aryl groups (e.g., those containing 6 to 15 carbonatoms), alkoxyl groups (e.g., those containing 1 to 15 carbon atoms),halogen atoms, a hydroxyl group and a phenylthio group.

X⁻ represents a non-nucleophilic anion, and examples thereof include thesame non-nucleophilic anions as the X⁻ in the formula (ZI) canrepresent.

Of the compounds capable of generating an acid upon irradiation with anactinic ray or radiation, compounds represented by the followingformulae (ZIV), (ZV) and (ZVI) can be preferred examples.

In the formulae (ZIV) to (ZVI), Ar₃ and Ar₄ each represent an aryl groupindependently.

R₂₂₆ represents an alkyl group, a cycloalkyl group or an aryl group.

R₂₂₇ and R₂₂₈ each represent an alkyl group, a cycloalkyl group, an arylgroup or an electron-attracting group. R₂₂₇ is preferably an aryl group.R₂₂₈ is preferably an electron-attracting group, far preferably a cyanogroup or a fluoroalkyl group.

A represents an alkylene group, an alkenylene group or an arylene group.

Of the compounds capable of generating acids upon irradiation with anactinic ray or radiation, the compounds represented by (ZI) to (ZIII)are preferred to the others.

The Compound (B) is preferably a compound capable of generating analiphatic sulfonic acid having a fluorine atom or atoms or abenzenesulfonic acid having a fluorine atom or atoms upon irradiationwith an actinic ray or radiation.

It is preferable that the Compound (B) has a triphenylsulfoniumstructure.

It is far preferable that the Compound (B) is a triphenylsulfonium saltcompound having in its cation part an alkyl or cycloalkyl group free offluorine substituent.

Examples of particularly preferred ones among the compounds capable ofgenerating acids upon irradiation with an actinic ray or radiation areillustrated below.

Photo-acid generators can be used alone or as combinations of two ormore thereof. When two or more types of photo-acid generators are usedin combination, it is preferable to combine compounds which can generatetwo types of organic acids differing by at least two in the total numberof constituent atoms except hydrogen atoms.

The content of photo-acid generators is preferably from 0.1 to 20 mass%, far preferably from 0.5 to 10 mass %, further preferably from 1 to 7mass %, based on the total solids in the resist composition. Byadjusting the content of photo-acid generators to fall within theforegoing range, the exposure latitude at the time of resist patternformation can be improved and the crosslinking reactivity with materialsfor forming a cross-linked layer can be increased.

(C) Solvent

Examples of a solvent which can be used in dissolving each of theingredients to prepare a resist composition include organic solvents,such as an alkylene glycol monoalkyl ether carboxylate, an alkyleneglycol monoalkyl ether, an alkyl lactate, an alkyl alkoxypropionate, a4-10C cyclic lactone, a 4-10C monoketone compound which may contain aring, an alkylene carbonate, an alkyl alkoxyacetate and an alkylpyruvate.

Suitable examples of an alkylene glycol monoalkyl ether carbonateinclude propylene glycol monomethyl ether acetate, propylene glycolmonoethyl ether acetate, propylene glycol monopropyl ether acetate,propylene glycol monobutyl ether acetate, propylene glycol monomethylether propionate, propylene glycol monoethyl ether propionate, ethyleneglycol monomethyl ether acetate, and ethylene glycol monoethyl etheracetate.

Suitable examples of an alkylene glycol monoalkyl ether includepropylene glycol monomethyl ether, propylene glycol monoethyl ether,propylene glycol monopropyl ether, propylene glycol monobutyl ether,ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether.

Suitable examples of an alkyl lactate include methyl lactate, ethyllactate, propyl lactate, and butyl lactate.

Suitable examples of an alkyl alkoxypropionate include ethyl3-ethoxypropionate, methyl 3-methoxypropionate, methyl3-ethoxypropionate, and ethyl 3-methoxypropionate.

Suitable examples of a 4-10C cyclic lactone include β-propiolactone,β-butyrolactone, γ-butyrolactone, α-methyl-γ-butyrolactone,β-methyl-γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-octanoiclactone, and α-hydroxy-γ-butyrolactone.

Suitable examples of a 4-10C monoketone compound which may contain aring include 2-butanone, 3-methylbutanone, pinacolone, 2-pentanone,3-pentanone, 3-methyl-2-pentanone, 4-methyl-2-pentanone,2-methyl-3-pentanone, 4,4-dimethyl-2-pentanone,2,4-dimethyl-3-pentanone, 2,2,4,4-tetramethyl-3-pentanone, 2-hexanone,3-hexanone, 5-methyl-3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone,2-methyl-3-heptanone, 5-methyl-3-heptanone, 2,6-dimethyl-4-heptanone,2-octanone, 3-octanone, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone,3-decanone, 4-decanone, 5-hexene-2-one, 3-pentene-2-one, cyclopentanone,2-methylcyclopentanone, 3-methylcyclopentanone,2,2-dimethycyclopentanone, 2,4,4-trimethylcyclopentanone, cyclohexanone,3-methylcyclohexanone, 4-methylcyclohexanone, 4-ethylcyclohexanone,2,2-dimethylcyclohexanone, 2,6-dimethylcyclohexanone,2,2,6-trimethylcyclohexanone, cycloheptanone, 2-methylcycloheptanone,and 3-methylcycloheptanone.

Suitable examples of an alkylene carbonate include propylene carbonate,vinylene carbonate, ethylene carbonate, and butylene carbonate.

Suitable examples of an alkyl alkoxyacetate includeacetate-2-methoxyethyl, acetate-2-ethoxyethyl,acetate-2-(2-ethoxyethoxy)ethyl, acetate-3-methoxy-3-methylbutyl, andacetate-1-methoxy-2-propyl.

Suitable examples of an alkyl pyruvate include methyl pyruvate, ethylpyruvate, and propyl pyruvate.

Examples of a solvent used to advantage include solvents having boilingpoints of 130° C. or above at ordinary temperatures and under normalatmospheric pressure. More specifically, such solvents includecyclopentanone, γ-butyrolactone, cyclohexanone, ethyl lactate, ethyleneglycol monoethyl ether acetate, propylene glycol monomethyl etheracetate, ethyl 3-ethoxypropionate, ethyl pyruvate,acetate-2-ethoxyethyl, acetate-2-(2-ethoxyethoxy)ethyl and propylenecarbonate.

In the invention, the solvents recited above may be used alone or ascombinations of two or more thereof.

The solvent used in the invention may also be a mixture of a solventhaving a hydroxyl group in its structure and a solvent having nohydroxyl group.

Examples of a solvent having a hydroxyl group include ethylene glycol,ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,propylene glycol, propylene glycol monomethyl ether, propylene glycolmonoethyl ether, and ethyl lactate. Of these solvents, propylene glycolmonomethyl ether and ethyl lactate are especially preferred to theothers.

Examples of a solvent having no hydroxyl group include propylene glycolmonomethyl ether acetate, ethyl ethoxypropionate, 2-heptanone,γ-butyrolactone, cyclohexanone, butyl acetate, N-methylpyrrolidone,N,N-dimethylacetamide, and dimethyl sulfoxide. Of these solvents,propylene glycol monomethyl ether acetate, ethyl ethoxypropionate,2-heptanone, γ-butyrolactone, cyclohexanone and butyl acetate are farpreferred to the others, and propylene glycol monomethyl ether acetate,ethyl ethoxypropionate and 2-heptanone are used to particular advantage.

The mixing ratio (by mass) between the solvent containing a hydroxylgroup and the solvent containing no hydroxyl group is from 1/99 to 99/1,preferably from 10/90 to 90/10, far preferably from 20/80 to 60/40. Amixed solvent containing a solvent having no hydroxyl group in aproportion of 50 weight % or above is particularly preferred from theviewpoint of coating evenness.

The solvent is preferably a solvent mixture of two or more kinds ofsolvents including propylene glycol monomethyl ether acetate.

The solids concentration in the present resist composition in a state ofbeing dissolved in a solvent is generally from 1.0 to 10 mass %,preferably from 2.0 to 5.7 mass %, far preferably from 2.0 to 5.3 mass%. The term “solids concentration” as used in the invention refers tothe percentage by mass of the total mass of all resist's ingredientsexcept solvent to the gross mass of the resist composition.

By adjusting the solids concentration to the range specified above, theresist solution can be applied evenly to the surface of a substrate, andbesides, it becomes possible to form resist patterns whose line edgeroughness is in a standout condition. Reasons for producing such effectsare not clear, but it is probably conceivable that aggregation ofingredients in the resist solution is inhibited by controlling solidsconcentration to 10 mass % or below, preferably 5.7 mass % or below; asa result, uniform resist film is formed.

(D) Resin Having at Least Either Fluorine or Silicon Atom

The resist composition for negative development according to theinvention preferably contains (D) a resin having at least either afluorine atom or a silicon atom (Resin (D)).

The fluorine atoms or silicon atoms in Resin (D) may be present in theresin's main chain, or they may constitute substituents in side chains.

The Resin (D) is preferably a resin having fluorinated alkyl groups,fluorinated cycloalkyl groups or fluorinated aryl groups asfluorine-containing partial structures.

The fluorinated alkyl group (preferably containing 1 to 10 carbon atoms,far preferably containing 1 to 4 carbon atoms) is a straight-chain orbranched alkyl group at least one hydrogen of which is substituted witha fluorine atom, which may further have another substituent.

The fluorinated cycloalkyl group is a mononuclear or polynuclearcycloalkyl group at least one hydrogen of which is substituted with afluorine atom, which may further have another substituent.

The fluorinated aryl group is an aryl group, such as a phenyl group or anaphthyl group, at least one hydrogen of which is substituted with afluorine atom, which may further have another substituent.

Examples of a fluorinated alkyl group, a fluorinated cycloalkyl groupand a fluorinated aryl group are illustrated below, but these examplesshould not be construed as limiting the scope of the invention.

In the formulae (f2) to (f4), R₅₇ to R₆₈, which are mutuallyindependent, each represent a hydrogen atom, a fluorine atom or an alkylgroup, provided that at least one of R₅₇ to R₆₁, at least one of R₆₂ toR₆₄, and at least one of R₆₅ to R₆₈ are each a fluorine atom or an alkylgroup (preferably containing 1 to 4 carbon atoms) at least one hydrogenof which is substituted with a fluorine atom. Herein, it is preferablethat all of R₅₇ to R₆₁ and all of R₆₅ to R₆₇ are fluorine atoms. Each ofR₆₂, R₆₃ and R₆₈ is preferably an alkyl group (preferably containing 1to 4 carbon atoms) at least one hydrogen of which is substituted with afluorine atom, far preferably a perfluoroalkyl group containing 1 to 4carbon atoms. R₆₂ and R₆₃ may combine with each other to form a ring.

The Resin (D) preferably has groups represented by the following formula(F3a) as its partial structures.

In the formula (F3a), R_(62a) and R_(63a), which are mutuallyindependent, each represent an alkyl group at least one hydrogen ofwhich is substituted with a fluorine atom. R_(62a) and R_(63a) maycombine with each other to form a ring.

R_(64a) represents a hydrogen atom, a fluorine atom or an alkyl group.

Examples of a group represented by the formula (f2) include ap-fluorophenyl group, a pentafluorophenyl group and a3,5-di(trifluoromethyl)phenyl group.

Examples of a group represented by the formula (f3) include atrifluoroethyl group, a pentafluoropropyl group, a pentafluoroethylgroup, a heptafluorobutyl group a hexafluoroisopropyl group, aheptafluoroisopropyl group, a hexafluoro(2-methyl)isopropyl group, anonafluorobutyl group, an octafluoroisobutyl group, a nonafluorohexylgroup, a nonafluoro-t-butyl group, a perfluoroisopentyl group, aperfluorooctyl group, a perfluoro(trimethyl)hexyl group, a2,2,3,3-tetrafluorocyclobutyl group and a perfluorocyclohexyl group. Ofthese groups, hexafluoroisopropyl, heptafluoroisopropyl,hexafluoro(2-methyl)isopropyl, octafluoroisobutyl, nonafluoro-t-butyland perfluoroisopentyl groups are preferable to the others, andhexafluoroisopropyl and heptafluoroisopropyl groups are far preferredover the others.

Examples of a group represented by the formula (f4) include —C(CF₃)₂OH,—C(C₂F₅)₂OH, —C(CF₃)(CH₃)OH and —CH(CF₃)OH. Of these groups, —C(CF₃)₂OHis preferred over the others.

It is also preferable that the Resin (D) is a resin having as itssilicon-containing partial structures alkylsilyl structures (preferablytrialkylsilyl groups) or cyclic siloxane structures.

Examples of an alkylsilyl or a cyclic siloxane structure include groupsrepresented by the following formulae (CS-1) to (CS-3).

In the formulae (CS-1) to (CS-3), R₁₂ to R₂₆, which are mutuallyindependent, each represent a straight-chain alkyl group (preferablycontaining 1 to 20 carbon atoms), or a branched alkyl or cycloalkylgroup (preferably containing 3 to 20 carbon atoms).

L₃ to L₅ each represent a single bond or a divalent linkage group.Examples of such a divalent linkage group include an alkylene group, aphenylene group, an ether group, a thioether group, a carbonyl group, anester group, an amide group, an urethane group, an urea group, andcombinations of two or more of the groups recited above.

n represents an integer of 1 to 5.

The Resin (D) is preferably a resin having repeating units of at leastone kind selected from among those represented by the following formulae(C-I) to (C-IV).

In the formulae (C-I) to (C-IV), R₁ to R₃, which are mutuallyindependent, each represent a hydrogen atom, a fluorine atom, a 1-4Cstraight-chain or branched alkyl group, or a 1-4C straight-chain orbranched fluoroalkyl group.

W₁ and W₂ each represent an organic group having at least either afluorine or silicon atom.

R₄ to R₇, which are mutually independent, each represent a hydrogenatom, a fluorine atom, a 1-4C straight-chain or branched alkyl group, ora 1-4C straight-chain or branched fluoroalkyl group; however at leastone of the substituents R₄ to R₇ is required to be a fluorine atom.Alternatively, R₄ and R₅, or R₆ and R₇ may combine with each other toform a ring.

R₈ represents a hydrogen atom, or a 1-4C straight-chain or branchedalkyl group.

R₉ represents a 1-4C straight-chain or branched alkyl group, or a 1-4Cstraight-chain or branched fluoroalkyl group.

L₁ and L₂ each represent a single bond or a divalent linkage group,which each have the same meaning as the foregoing L₃ to L₅ each have.

Q represents a mononuclear or polynuclear cyclic aliphatic group. Morespecifically, it represents atoms including two carbon atoms bondedtogether (C—C) and forming an alicyclic structure.

The formula (C-I) is far preferably any of the following formulae (C-Ia)to (C-Id).

In the formulae (C-Ia) to (C-Id), R₁₀ and R₁₁ each represent a hydrogenatom, a fluorine atom, a 1-4C straight-chain or branched alkyl group ora 1-4C straight-chain or branched fluoroalkyl group.

W₃ to W₆ each represent an organic group having at least either one ormore fluorine atoms, or one or more silicon atoms.

When W₁ to W₆ are fluorine-containing organic groups, each organic groupis preferably a 1-20C straight-chain, branched or cyclic fluorinatedalkyl group or cyclo alkyl group, or a 1-20C straight-chain, branched orcyclic fluorinated alkyl ether group.

Examples of the fluorinated alkyl group of W₁ to W_(o) each include atrifluoroethyl group, a pentafluoropropyl group, a hexafluoroisopropylgroup, a hexafluoro(2-methyl)isopropyl group, a heptafluorobutyl group,a heptafluoroisopropyl group, an octafluoroisobutyl group, anonafluorohexyl group, a nonafluoro-t-butyl group, a perfluoroisopentylgroup, a perfluorooctyl group and a perfluoro(trimethyl)hexyl group.

When W₁ to W₆ are silicon-containing organic groups, each organic grouppreferably has an alkylsilyl or cyclic siloxane structure. Examples ofsuch a group include groups represented by the formulae (CS-1), (CS-2)and (CS-3).

Examples of a repeating unit represented by the formula (C-I) areillustrated below. In the following structural formulae, X represents ahydrogen atom, —CH₃, —F or —CF₃

The Resin (D) is preferably a resin selected from the following resins(D-1) to (D-6).

(D-1): A resin that has (a) repeating units containing fluoroalkylgroups (preferably 1-4C fluoroalkyl groups), far preferably a resinhaving only the repeating units (a).

(D-2): A resin that has (b) repeating units containing trialkylsilylgroups or cyclic siloxane structures, far preferably a resin having onlythe repeating units (b),

(D-3): A resin that has (a) repeating units containing fluoroalkylgroups (preferably 1-4C fluoroalkyl groups) and (c) repeating unitscontaining branched alkyl groups (preferably 4-20C branched alkylgroups), cycloalkyl groups (preferably 4-20C cycloalkyl groups),branched alkenyl groups (preferably 4-20C branched alkenyl groups),cycloalkenyl groups (preferably 4-20C cycloalkyl groups) or aryl groups(preferably 4-20C aryl groups), far preferably a copolymer resinconstituted of the repeating units (a) and the repeating units (c).

(D-4): A resin that has (b) repeating units containing trialkylsilylgroups or cyclic siloxane structures and (c) repeating units containingbranched alkyl groups (preferably 4-20C branched alkyl groups),cycloalkyl groups (preferably 4-20C cycloalkyl groups), branched alkenylgroups (preferably 4-20C branched alkenyl groups), cycloalkenyl groups(preferably 4-20C cycloalkyl groups) or aryl groups (preferably 4-20Caryl groups), far preferably a copolymer resin constituted of therepeating units (b) and the repeating units (c).

(D-5) A resin that has (a) repeating units containing fluoroalkyl groups(preferably 1-4C fluoroalkyl groups) and (b) repeating units containingtrialkylsilyl groups or cyclic siloxane structures, far preferably acopolymer resin constituted of the repeating units (a) and the repeatingunits (b).

(D-6): A resin that has (a) repeating units containing fluoroalkylgroups (preferably 1-4C fluoroalkyl groups), (b) repeating unitscontaining trialkylsilyl groups or cyclic siloxane structures and (c)repeating units containing branched alkyl groups (preferably 4-20Cbranched alkyl groups), cycloalkyl groups (preferably 4-20C cycloalkylgroups), branched alkenyl groups (preferably 4-20C branched alkenylgroups), cycloalkenyl groups (preferably 4-20C cycloalkyl groups) oraryl groups (preferably 4-20C aryl groups), far preferably a copolymerresin constituted of the repeating units (a), the repeating units (b)and the repeating units (c).

Into the repeating units (c) which contain branched alkyl groups,cycloalkyl groups, branched alkenyl groups, cycloalkenyl groups or arylgroups and are constituents of each of the resins (D-3), (D-4) and(D-6), appropriate functional groups can be introduced withconsideration given to a balance between hydrophilic and hydrophobicproperties and mutual interactivity. However, it is preferred in pointof receding contact angle that the functional groups introduced be polargroup-free functional groups.

In the resins (D-3), (D-4) and (D-6), the proportion offluoroalkyl-containing repeating units (a), or the proportion oftrialkylsilyl- or cyclic siloxane-containing repeating units (b), or thetotal proportion of the repeating units (a) and the repeating units (b)is preferably from 20 to 99 mole %.

The Resin (D) is preferably a resin having repeating units representedby the following formula (Ia).

In the formula (Ia), Rf represents a hydrogen atom, a fluorine atom oran alkyl group at least one hydrogen atom of which is substituted with afluorine atom.

R₁ represents an alkyl group.

R₂ represents a hydrogen atom or an alkyl group.

The alkyl group at least one hydrogen atom of which is substituted witha fluorine atom, which is represented by Rf in the formula (Ia),preferably contains 1 to 3 carbon atoms, and it is far preferably atrifluoromethyl group.

The alkyl group of R₁ in the formula (Ia) is preferably a 3-10Cstraight-chain or branched alkyl group, far preferably a 3-10C branchedalkyl group.

The alkyl group of R₂ in the formula (Ia) is preferably a 1-10Cstraight-chain or branched alkyl group.

Examples of a repeating unit represented by the formula (Ia) areillustrated below, but these examples should not be construed aslimiting the scope of the invention. X in the following structuralformulae each represents a hydrogen atom, a fluorine atom or atrifluoromethyl group (—CF₃).

The repeating units represented by the formula (Ia) can be formed bypolymerizing a compound represented by the following formula (I).

In the formula (I), Rf represents a hydrogen atom, a fluorine atom or analkyl group at least one hydrogen atom of which is substituted with afluorine atom.

R₁ represents an alkyl group.

R₂ represents a hydrogen atom or an alkyl group.

Rf, R₁ and R₂ in the formula (I) have the same meanings as Rf, R₁ and R₂in the formula (Ia), respectively.

As to the compound represented by the formula (I), a commerciallyavailable product may be used, or a compound prepared by synthesis maybe used. The synthesis can be achieved by converting2-trifluoromethylmethacrylic acid into its acid chloride and thenesterifying the acid chloride.

The Resin (D) is preferably a resin having repeating units representedby the following formula (II) and repeating units represented by thefollowing formula (III).

In the formulae (II) and (III), Rf represents a hydrogen atom, afluorine atom or an alkyl group at least one hydrogen atom of which issubstituted with a fluorine atom.

R₃ represents an alkyl group, a cycloalkyl group, an alkenyl group or acycloalkenyl group.

R₄ represents an alkyl group, a cycloalkyl group, an alkenyl group, acycloalkenyl group, a trialkylsilyl group or a group having a cyclicsiloxane structure. L₆ represents a single bond or a linkage group.

0<m<100, and 0<n<100.

Rf in the formula (II) has the same meaning as Rf in the formula (Ia)has.

The alkyl group of R₃ is preferably a 3-20C straight-chain or branchedalkyl group.

The cycloalkyl group of R₃ is preferably a 3-20C cycloalkyl group.

The alkenyl group of R₃ is preferably a 3-20C alkenyl group.

The cycloalkenyl group of R₃ is preferably a 3-20C cycloalkenyl group.

As to m and n, cases where m is from 30 to 70 and n is from 30 to 70 arepreferred, and cases where m is from 40 to 60 and n is from 40 to 60 arefar preferred.

The alkyl group of R₄ in the formula (III) is preferably a 3-20Cstraight-chain or branched alkyl group.

The cycloalkyl group of R₄ is preferably a 3-20C cycloalkyl group.

The alkenyl group of R₄ is preferably a 3-20C alkenyl group.

The cycloalkenyl group of R₄ is preferably a 3-20C cycloalkenyl group.

The trialkylsilyl group of R₄ is preferably a 3-20C trialkylsilyl group.

The group of R₄ which has a cyclic siloxane structure is preferably agroup having a 3-20C cyclic siloxane structure.

The divalent linkage group of L₆ is preferably an alkylene group (farpreferably a 1-5C alkylene group), or an oxy group (—O—).

Examples of Resin (D) having repeating units represented by the formula(Ia) are illustrated below, but these examples should not be construedas limiting the scope of the invention.

The Resin (D) may further have repeating units represented by thefollowing formula (VIII).

In the formula (VIII), Z₂ represents —O— or —N(R₄₁)—. R₄₁ represents ahydrogen atom, an alkyl group or —OSO₂—R₄₂. R42 represents an alkylgroup, a cycloalkyl group or a camphor residue. The alkyl groups of R₄₁and R₄₂ may be substituted with halogen atoms (preferably fluorineatoms) or the like.

It is preferred that the Resin (D) be stable to an acid and insoluble inan alkali developer. In addition, the Resin (D) is preferably a resinsoluble in a negative developer.

To be specific, in point of not only stability to an acid andinsolubility in an alkali developer but also following capability of animmersion liquid, it is preferable that the Resin (D) has neitheralkali-soluble groups nor groups capable of increasing its solubility ina developer by the action of an acid or an alkali.

In the Resin (D), it is appropriate that the sum total of repeatingunits having alkali-soluble groups and those having groups capable ofincreasing solubility in a developer by the action of an acid or analkali make up no higher than 20 mole %, preferably from 0 to 10 mole %,far preferably from 0 to 5 mole %, of all repeating units of the Resin(D).

Furthermore, the presence of hydrophilic polar groups in the Resin (D)tends to degrade the following capability of an immersion liquid, so itis preferable that the Resin (D) is free of polar groups chosen fromhydroxyl, alkylene glycol, ether or sulfone groups.

Examples of (x) an alkali-soluble group include a phenolic hydroxylgroup, a carboxylic acid group, a fluorinated alcohol group, a sulfonicacid group, a sulfonamido group, a sulfonylimido group, an(alkylsulfonyl)(alkylcarbonyl)methylene group, an(alkylsulfonyl)(alkylcarbonyl)imido group, a bis(alkylcarbonyl)methylenegroup, a bis(alkylcarbonyl)imido group, a bis(alkylsulfonyl)methylenegroup, a bis(alkylsulfonyl)imido group, a tris(alkylcarbonyl)methylenegroup and a tris(alkylsulfonyl)methylene group.

Examples of (y) a group capable of decomposing by the action of analkali (alkali developer) and increasing solubility in an alkalideveloper include a lactone group, an ester group, a sulfonamido group,an acid anhydride residue and an acid imido group.

Examples of (z) a group capable of decomposing by the action of an acidand increasing solubility in a developer include the same groups as theacid-decomposable groups recited in the description of theacid-decomposable Resin (A).

On the other hand, the repeating units represented by the followingformula (pA-c) undergo no decomposition or extremely slightdecomposition by the action of an acid, as compared withacid-decomposable groups in the Resin (A), so their decomposability isconsidered to be equal to substantially zero.

In the formula (pA-c), Rp₂ represents a hydrocarbon group having atertiary carbon atom attached to the oxygen atom in the formula.

When Resin (D) contains silicon atoms, the silicon content is preferablyfrom 2 to 50 mass %, far preferably from 2 to 30 mass %, of themolecular weight of the Resin (D). And the proportion of repeating unitscontaining silicon atoms is preferably from 10 to 100 mass %, farpreferably from 20 to 100 mass %, with respect to all repeating unitsconstituting the Resin (D).

When Resin (D) contains fluorine atoms, the fluorine content ispreferably from 5 to 80 mass %, far preferably from 10 to 80 mass %, ofthe molecular weight of the Resin (D). And the proportion of repeatingunits containing fluorine atoms is preferably from 10 to 100 mass %, farpreferably from 30 to 100 mass %, with respect to all repeating unitsconstituting the Resin (D).

The weight average molecular weight of Resin(D) is preferably from 1,000to 100,000, far preferably from 1,000 to 50,000, further preferably from2,000 to 15,000, as calculated in terms of standard polystyrene.

The Resin (D) having polydispersity (molecular weight distribution) from1 to 5 is generally used, and the polydispersity thereof is preferablyfrom 1 to 3, far preferably from 1 to 2, particularly preferably from 1to 1.7. The smaller the polydispersity value, the better the roughnessquality.

The residual monomer content in Resin (D) is preferably from 0 to 10mass %, far preferably from 0 to 5 mass %, further preferably from 0 to1 mass %. From the viewpoints of resolution, resist profile and resistsidewall roughness, the molecular weight distribution (Mw/Mn, referredto as polydispersity too) of Resin (D) is preferably in a range of 1 to5, far preferably in a range of 1 to 3, further preferably in a range of1 to 1.5.

The amount of Resin (D) mixed in a resist composition for negativedevelopment is preferably from 0.1 to 5 mass %, far preferably from 0.2to 3.0 mass %, further preferably from 0.3 to 2.0 mass %, based on thetotal solids in the resist composition.

It is only natural that Resin (D) is minimized in content of impurities,such as metal, in common with the acid-decomposable Resin (A), andbesides, it is preferred that the total content of monomer residues andoligomer components in Resin (D) be reduced to a specified value, e.g.,0.1 mass % or below as measured by HPLC. By this reduction, thesensitivity, resolution, process consistency and pattern profile ofresist can further be improved, and besides, the resist free ofsubmerged extraneous matter, sensitivity deterioration with lapse oftime and so on can be obtained.

Various commercial products can be utilized as Resin (D), while Resin(D) may be synthesized according to a general method (e.g., radicalpolymerization). As examples of a general synthesis method, there areknown a batch polymerization method in which polymerization is carriedout by dissolving monomer species and an initiator in a solvent andheating them, and a drop polymerization method in which a solutioncontaining monomer species and an initiator is added dropwise to aheated solvent over 1 to 10 hours. However, the drop polymerizationmethod is preferable to the batch polymerization method. Examples of asolvent usable in the polymerization reaction include ethers, such astetrahydrofuran, 1,4-dioxane and diisopropyl ether; ketones, such asmethyl ethyl ketone and methyl isobutyl ketone; ester solvents, such asethyl acetate; amide solvents, such as dimethylformamide anddimethylacetamide; and solvents as described hereafter in which thepresent composition can be dissolved, such as propylene glycolmonomethyl ether acetate, propylene glycol monomethyl ether andcyclohexanone. It is preferred that the polymerization be carried outusing the same solvent as used in the resist composition according tothe invention. By use of a common solvent, it becomes possible toprevent particles from developing during the storage.

The polymerization reaction is preferably carried out in an atmosphereof inert gas, such as nitrogen or argon. And the polymerization isinitiated by use of a commercially available radical initiator (e.g., anazo-type initiator or peroxide) as polymerization initiator. The radicalinitiator is preferably an azo-type initiator, and more specifically, anazo-type initiator having an ester group, a cyano group or a carboxylgroup. Examples of such a preferred azo-type initiator includeazobisisobutyronitrile, azobisdimethylvaleronitrile and dimethyl2,2′-azobis(2-methylpropionate). The concentration of reaction speciesis generally from 5 to 50 mass %, preferably from 30 to 50 mass %, andthe reaction temperature is generally from 10° C. to 150° C., preferablyfrom 30° C. to 120° C., far preferably from 60° C. to 100° C.

After the reaction is completed, the reaction product is allowed tostand and cooled to room temperature, and then subjected topurification. For the purification, a usual method is applicable, andexamples thereof include a liquid-liquid extraction method in whichresidual monomers and oligomeric components are eliminated by washingwith water or by combined use of appropriate solvents, a method ofperforming purification in a solution state, such as an ultrafiltrationmethod in which only components of molecular weight lower than aspecific value are extracted and eliminated, a reprecipitation method inwhich a resin solution is dripped into a poor solvent to result incoagulation of the resin and elimination of residual monomers and so on,and a method of performing purification in a solid state, such as amethod of washing filtered resin slurry with a poor solvent. Forinstance, the reaction solution is brought into contact with an at most10-fold, preferably 10- to 5-fold, volume of solvent (poor solvent) inwhich the resin is slightly soluble or insoluble, thereby precipitatingthe intended resin as a solid.

As the solvent used in the operation of precipitation or reprecipitationfrom a polymer solution (precipitation or reprecipitation solvent), anysolvent can serve so long as it is a poor solvent of the polymer. Andthe solvent to be used in such an operation can be selectedappropriately from the following poor solvents according to the kind ofthe polymer. Specifically, the poor solvents include hydrocarbons (suchas aliphatic hydrocarbons including pentane, hexane, heptane and octane;alicyclic hydrocarbons including cyclohexane and methylcyclohexane; andaromatic hydrocarbons including benzene, toluene and xylene);halogenated hydrocarbons (such as aliphatic halogenated hydrocarbonsincluding methylene chloride, chloroform and carbon tetrachloride; andaromatic halogenated hydrocarbons including chlorobenzene anddichlorobenzene); nitro compounds (such as nitromethane andnitroethane); nitriles (such as acetonitrile and benzonitrile); ethers(such as linear ethers including diethyl ether, diisopropyl ether anddimethoxyethane; and cyclic ethers including tetrahydrofuran anddioxane); ketones (such as acetone, methyl ethyl ketone and diisobutylketone); esters (such as ethyl acetate and butyl acetate); carbonates(such as dimethyl carbonate, diethyl carbonate, ethylene carbonate andpropylene carbonate); alcohols (such as methanol, ethanol, propanol,isopropyl alcohol and butanol); carboxylic acids (such as acetic acid);water: and mixed solvents containing the solvents recited above. Ofthese solvents, solvents containing at least alcohol (especiallymethanol) or water are preferred as precipitation or reprecipitationsolvents. In such a mixed solvent containing at least a hydrocarbon, theratio of alcohol (especially methanol) to other solvents (e.g., esterssuch as ethyl acetate, ethers such as tetrahydrofuran), thealcohol/other solvents ratio, by volume at 25° C. is preferably of theorder of 10/90 to 99/1, far preferably of the order of 30/70 to 98/2,further preferably of the order of 50/50 to 97/3.

The amount of a precipitation or reprecipitation solvent used can bechosen appropriately with consideration given to efficiency and yield,and it is generally from 100 to 10,000 parts by mass, preferably from200 to 2,000 parts by mass, far preferably from 300 to 1,000 parts bymass, per 100 parts by mass of polymer solution.

The bore of a nozzle used for feeding a polymer solution into aprecipitation or reprecipitation solvent (poor solvent) is preferably 4mm4) or below (e.g., 0.2 to 4 mm(O). And the linear speed at which apolymer solution is fed (dripped) into a poor solvent is, e.g., from 0.1to 10 m/sec, preferably of the order of 0.3 to 5 m/sec.

The precipitation or reprecipitation is preferably carried out withstirring. Examples of stirring blades usable for stirring include a deskturbine, a fan turbine (including paddles), a curved-blade turbine, afeather turbine, blades of Phaudler type, blades of Bullmargin type, anangle-blade fan turbine, propellers, multistage-type blades, anchor-type(horseshoe-type) blades, gate-type blades, double ribbon-type blades andscrews. It is preferable that the stirring is continued for additional10 minutes or above, especially 20 minutes or above, after the polymersolution feed is completed. When the stirring time is insufficient,there occurs a case where the monomer content in polymer particlescannot be reduced properly. Instead of using stirring blades, a polymersolution and a poor solvent may be mixed together by using a line mixer.

The precipitation or reprecipitation temperature can be chosenappropriately with consideration given to efficiency and operationalease, and it is usually from 0° C. to 50° C., preferably in the vicinityof room temperature (e.g., from, 20° C. to 35° C.). In order to performthe precipitation or reprecipitation operation, a commonly-used mixingvessel, such as a stirred tank, and a hitherto known process, such as abatch process or a continuous process, can be utilized.

The polymer particles precipitated or reprecipitated are generallysubjected to solid-liquid separation, such as filtration orcentrifugation, and then dried. Thus, the polymer particles are madeavailable for use. The filtration is carried out using asolvent-resistant filtering material, preferably under a pressurizedcondition. The drying is performed at a temperature of the order of 30°C. to 100° C., preferably of the order of 30° C. to 50° C., under anormal pressure or a reduced pressure, preferably under a reducedpressure.

Additionally, resin once precipitated and separated out of its solutionmay be dissolved in a solvent again and brought into contact with asolvent in which the resin is slightly soluble or insoluble.

More specifically, it is acceptable to adopt a method which includesbringing a reaction solution after finishing radical polymerizationreaction into contact with a solvent in which the polymer produced isslightly soluble or insoluble, thereby precipitating the polymer asresin (process step a), separating the resin from the solution (processstep b), preparing a resin solution A by dissolving the resin in asolvent again (process step c), bringing the resin solution A intocontact with a solvent, in which the resin is slightly soluble orinsoluble, the volume of which is lower than 10 times, preferably nohigher than 5 times, the volume of the resin solution A, therebyprecipitating the resin as a solid (process step d), and separating theprecipitated resin out of the resultant solution (process step e).

The solvent used when the resin solution A is prepared may be a solventsimilar to the solvent used in dissolving monomer(s) for polymerizationreaction, and it may be one and the same as or different from thesolvent used in the polymerization reaction.

Examples of Resin (D) are illustrated below, but these examples shouldnot be construed as limiting the scope of the invention.

(E) Basic Compound

For reduction of performance changes occurring with the passage of timefrom exposure to heating, it is appropriate that the resist compositionfor use in the invention contain (E) a basic compound.

Examples of a compound suitable as the basic compound include compoundshaving structures represented by the following (A) to (E).

In the formulae (A) and (E), R²⁰⁰, R²⁰¹ and R²⁰² may be the same ordifferent, and each of them represents a hydrogen atom, an alkyl group(preferably a 1-20C alkyl group), a cycloalkyl group (preferably a 3-20Ccycloalkyl group) or an aryl group (containing 6 to 20 carbon atoms).Herein, R²⁰¹ and R²⁰² may combine with each other to form a ring.

When the foregoing alkyl group has a substituent, a 1-20C aminoalkylgroup, a 1-20C hydroxyalkyl group or a 1-20C cyanoalkyl group issuitable as the substituted alkyl group.

In the formula (E), R²⁰³, R²⁰⁴, R²⁰⁵, and R²⁰⁶ may be the same ordifferent, and each of them represents a 1-20C alkyl group.

The alkyl groups in the formulae (A) to (E) are preferably unsubstitutedalkyl groups.

Examples of preferred basic compounds include guanidine,aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine,aminoalkylmorpholine and piperidine. Examples of far preferred compoundsinclude compounds having an imidazole structure, a diazabicyclostructure, an onium hydroxide structure, an onium carboxylate structure,a trialkylamine structure, an aniline structure and a pyridinestructure, respectively; an alkylamine derivative having a hydroxylgroup and/or an ether linkage; and an aniline derivative having ahydroxyl group and/or an ether linkage.

Examples of the compound having an imidazole structure includeimidazole, 2,4,5-triphenylimidazole and benzimidazole. Examples of thecompound having a diazabicyclo structure include1,4-diazabicyclo[2.2.2]octane, 1,5-diazabicyclo[4.3.0]nona-5-ene and1,8-d iazabicyclo[5.4.0]undeca-7-ene. Examples of the compound having anonium hydroxide structure include triarylsulfonium hydroxides,phenacylsulfonium hydroxides and sulfonium hydroxides having 2-oxoalkylgroups, and more specifically, they include triphenylsulfoniumhydroxide, tris(t-butylphenyl)sulfonium hydroxide,bis(t-butylphenyl)iodonium hydroxide, phenacylthiophenium hydroxide and2-oxopropylthiophenium hydroxide. The compound having an oniumcarboxylate structure is a compound having the structure correspondingto the substitution of carboxylate for the anion moiety of the compoundhaving an onium hydroxide structure, with examples including acetate,adamantane-1-carboxylate and perfluoroalkylcarboxylates. Examples of thecompound having a trialkylamine structure include tri(n-butyl)amine andtri(n-octyl)amine. Examples of the aniline compound include2,6-diisopropylaniline, N,N-dimethylaniline, N,N-dibutylaniline andN,N-dihexylaniline. Examples of the alkylamine derivative having ahydroxyl group and/or an ether linkage include ethanolamine,diethanolamine, triethanolamine and tris(methoxyethoxyethyl)amine. Anexample of the aniline derivative having a hydroxyl group and/or anether linkage is N,N-bis(hydroxyethyl)aniline.

These basic compounds are used alone or as combinations of two or morethereof.

The amount of basic compounds used is generally from 0.001 to 10 mass %,preferably 0.01 to 5 mass %, based on the total solids in the resistcomposition.

The ratio between the amount of acid generator(s) used and the amount ofbasic compound(s) used in the composition, the acid generator/basiccompound ratio (by mole), is preferably from 2.5 to 300. Morespecifically, it is appropriate that the ratio by mole be adjusted to atleast 2.5 in point of sensitivity and resolution, and that it beadjusted to at most 300 from the viewpoint of preventing degradation inresolution by thickening of resist patterns with the passage of timefrom the end of exposure to heating treatment. The acid generator/basiccompound ratio (by mole) is preferably from 5.0 to 200, far preferablyfrom 7.0 to 150.

(F) Surfactant

It is preferable that the resist composition for use in the inventionfurther contains (F) a surfactant, specifically a surfactant containingat least one fluorine atom and/or at least one silicon atom (either afluorine-containing surfactant, or a silicon-containing surfactant, or asurfactant containing both fluorine and silicon atoms), or a combinationof at least two of these surfactants.

Incorporation of such a surfactant in the resist composition for use inthe invention allows production of resist patterns having strongadhesion and reduced development defect while ensuring the compositionboth satisfactory sensitivity and high resolution in the case of usingan exposure light source of 250 nm or below, especially 220 nm or below.

Examples of a surfactant containing at least one fluorine atom and/or atleast one silicon atom include the surfactants disclosed inJP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950,JP-A-63-34540, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988,JP-A-2002-277862, and U.S. Pat. Nos. 5,405,720, 5,360,692, 5,529,881,5,296,330, 5,436,098, 5,576,143, 5,294,511 and 5,824,451. In addition,the following commercially available surfactants can also be used asthey are.

Examples of commercial surfactants which can be used include fluorine-or silicon-containing surfactants, such as EFTOP EF301 and EF303(produced by Shin-Akita Kasei K.K.), Florad FC430, 431 and 4430(produced by Sumitomo 3M, Inc.), Megafac F171, F173, F176, F189, F113,F110, F177, F120 and R⁰⁸ (produced by Dainippon Ink & Chemicals, Inc.),Surflon S-382, SC101, 102, 103, 104, 105 and 106 (produced by AsahiGlass Co., Ltd.), Troysol S-366 (produced by Troy Chemical Industries,Inc.), GF-300 and GF-150 (produced by Toagosei Co., Ltd.), Surflon S-393(produced by Seimi Chemical Co., Ltd.), EFTOP EF121, EF122A, EF122B,RF122C, EF125M, EF135M, EF351, EF352, EF801, EF802 and EF601 (producedby JEMCO Inc.), PF636, PF656, PF6320 and PF6520 (produced by OMNOVASolutions Inc.), and FTX-204D, 208G, 218G, 230G, 204D, 208D, 212D, 218Dand 222D (produced by NEOS). Moreover, organosiloxane polymer KP-341(produced by Shin-Etsu Chemical Co., Ltd.) can be used as asilicon-containing surfactant.

In addition to the heretofore known surfactants as recited above,surfactants utilizing polymers having fluorinated aliphatic groupsderived from fluorinated aliphatic compounds synthesized by atelomerization method (also referred to as a telomer method) or anoligomerization method (also referred to as an oligomer method) can beused. These fluorinated aliphatic compounds can be synthesized accordingto the methods disclosed in JP-A-2002-90991.

The polymers having fluorinated aliphatic groups are preferablycopolymers of fluorinated aliphatic group-containing monomers and(poly(oxyalkylene)) acrylates and/or (poly(oxyalkylene)) methacrylates,wherein the fluorinated aliphatic group-containing units may bedistributed randomly or in blocks. Examples of such a poly(oxyalkylene)group include a poly(oxyethylene) group, a poly(oxypropylene) group anda poly(oxybutylene) group. In addition, the poly(oxyalkylene) group maybe a unit containing alkylene groups of different chain lengths in itsoxyalkylene chain, such as poly(oxyethylene block/oxypropyleneblock/oxyethylene block combination) and poly(oxyethyleneblock/oxypropylene block combination). Further, the copolymers offluorinated aliphatic group-containing monomers and (poly(oxyalkylene))acrylates (or methacrylates) may be not only binary copolymers but alsoternary or higher copolymers prepared using in each individualcopolymerization at least two different kinds of fluorinated aliphaticgroup-containing monomers or/and at least two different kinds of(poly(oxyalkylene)) acrylates (or methacrylates) at the same time.

Examples of commercially available surfactants of such types includeMegafac F178, F-470, F-473, F-475, F-476 and F-472 (produced byDainippon Ink & Chemicals, Inc.). Additional examples of surfactants ofsuch types include a copolymer of C₆F₁₃ group-containing acrylate (ormethacrylate) and poly(oxyalkylene) acrylate (or methacrylate), and acopolymer of C₃F₇ group-containing acrylate (or methacrylate),poly(oxyethylene) acrylate (or methacrylate) and poly(oxypropylene)acrylate (or methacrylate).

Alternatively, it is also possible to use surfactants other thansurfactants containing fluorine and/or silicon atoms. Examples of suchsurfactants include nonionic surfactants, such as polyoxyethylene alkylethers (e.g., polyoxyethylene lauryl ether, polyoxyethylene stearylether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether),polyoxyethylene alkyl aryl ethers (e.g., polyoxyethylene octyl phenolether, polyoxyethylene nonyl phenol ether),polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acidesters (e.g., sorbitan monolaurate, sorbitan monopalmitate, sorbitanmonostearate, sorbitan monooleate, sorbitan trioleate, sorbitantristearate), and polyoxyethylene sorbitan fatty acid esters (e.g.,polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitanmonopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylenesorbitan trioleate, polyoxyethylene sorbitan tristearate).

These surfactants may be used alone or as combinations of two or morethereof.

The amount of a surfactant (F) used is preferably from 0.01 to 10 mass%, preferably 0.1 to 5 mass %, based on the total ingredients (exclusiveof a solvent) in the resist composition.

(G) Onium Salt of Carboxylic Acid

The resist composition for use in the invention may further contain (G)an onium salt of carboxylic acid. Examples of such an onium salt ofcarboxylic acid (G) include sulfonium carboxylates, iodoniumcarboxylates and ammonium carboxylates. Of these onium salts, iodoniumsalts and sulfonium salts are especially preferred. In addition, it ispreferable that neither aromatic group nor carbon-carbon double bond ispresent in the carboxylate residue of an onium carboxylate (G) used inthe invention. As the anion part of (G), 1-30C straight-chain andbranched alkyl carboxylate anions and mononuclear or polynuclearcycloalkyl carboxylate anions are especially suitable. Of these anions,the carboxylate anions whose alkyl groups are partially or entirelysubstituted with fluorine atoms are preferred over the others. Inaddition, those alkyl chains may contain oxygen atoms. Incorporation ofan onium salt having such a carboxylate anion into a resist compositioncan ensure the resist composition transparency to light with wavelengthsof 220 nm or below, and allows increases in sensitivity and resolution,and improvements in iso/dense bias and exposure margin.

Examples of a fluorinated carboxylate anion include a fluoroacetateanion, a difluoroacetate anion, a trifluoroacetate anion, apentafluoropropionate anion, a heptafluorobutyrate anion, anonafluoropentanate anion, a perfluorododecanate anion, aperfluorotridecanate anion, a perfluorocyclohexanecarboxylate anion anda 2,2-bistrifluoromethylpropionate anion.

The onium carboxylate (G) as recited above can be synthesized byallowing an onium hydroxide, such as sulfonium hydroxide, iodoniumhydroxide or ammonium hydroxide, and a carboxylic acid to react withsilver oxide in an appropriate solvent.

The suitable content of an onium salt of carboxylic acid (G) in acomposition is generally from 0.1 to 20 mass %, preferably from 0.5 to10 mass %, far preferably from 1 to 7 mass %, based on the total solidsin the composition.

(H) Other Additives

The resist composition for use in the invention can further contain, onan as needed basis, dyes, plasticizers, photosensitizers, lightabsorbents, alkali-soluble resins, dissolution inhibitors and compoundswhich can promote dissolution in developers (e.g., phenol compoundshaving molecular weights of 1,000 or below, alicyclic or aliphaticcompounds having carboxyl groups).

The phenol compounds which are 1,000 or below in molecular weight can beeasily synthesized by persons skilled in the art when they refer to themethods as disclosed in JP-A-4-122938, JP-A-2-28531, U.S. Pat. No.4,916,210 and European Patent No. 219,294.

Examples of alicyclic or aliphatic compounds having carboxyl groupsinclude carboxylic acid derivatives having steroid structures, such ascholic acid, deoxycholic acid and lithocholic acid, adamantanecarboxylicacid derivatives, adamantanedicarboxylic acid, cyclohexanecarboxylicacid and cyclohexanedicarboxylic acid, but they are not limited to thecompounds recited above.

EXAMPLES

The invention is illustrated below in more detail by reference to thefollowing examples, but these examples should not be construed aslimiting the scope of the invention in any way.

Synthesis Example 1 Synthesis of Resin (D20))

In propylene glycol monomethyl ether acetate, 47.2 g ofhexafluoroisopropyl acrylate (a product of Wako Pure ChemicalIndustries, Ltd.) is dissolved, thereby preparing 170 g of a solutionhaving a solid concentration of 20%. To this solution, 8 mole % (3.68 g)of a polymerization initiator V-601 (a product of Wako Pure ChemicalIndustries, Ltd.) is added. In an atmosphere of nitrogen, the resultantsolution is added dropwise over 4 hours to 20.0 g of propylene glycolmonomethyl ether acetate heated to 80° C. After the conclusion ofdropwise addition, the reaction solution is stirred for 2 hours, therebyobtaining a Reaction Solution (1). After the completion of the reaction,the Reaction Solution (1) is cooled to room temperature, and then addeddropwise to a twenty-times greater amount of 8:1 methanol-water solventmixture. An oily compound thus separated is collected by decantation toyield 24.1 g of the intended Resin (D20).

The weight average molecular weight of Resin (D20) measured by GPC andcalculated in terms of standard polystyrene is 7,600, and thepolydispersity (Mw/Mn) of Resin (D20) is 1.6.

Other resins of Component (D) used in Examples are synthesized insimilar manners to the above. The structures of resins synthesizedherein as Component (D) are the same as those hereinbefore shown as theexamples of Resin (D). The ratio (by mole) between structural units,weight average molecular weight and polydispersity of Resin (D) used ineach Example are summarized in Table 1.

TABLE 1 Resin (D) Ratio between Compound Structural Units Code Mw Mw/Mn(by mole) D-8  5,500 1.5 50/50 D-11 7,500 1.62 60/40 D-14 11,000 2 80/20D-15 9,000 1.65 30/70 D-20 7,600 1.6 100 D-25 15,000 1.8 50/50 D-308,000 1.9 50/50 D-60 12,000 1.95 50/10/40 D-74 8,000 1.75 40/60

Synthesis Example 2 Synthesis of Resin (A1)

In a stream of nitrogen, 20 g of 6:4 (by mass) solvent mixture ofpropylene glycol mnomethyl ether acetate and propylene glycol monomethylether is put in a three-necked flask and heated up to 80° C. (Solvent1). A monomer mixture composed of γ-butyrolactone methacrylate,hydroxyadamantane methacrylate and 2-methyl-2-adamantyl methacrylate inproportions of 40:25:35 by mole is added to a 6:4 (by mass) solventmixture of propylene glycol monomethyl ether acetate and propyleneglycol monomethyl ether, thereby preparing a 22 mass % monomer solution(200 g). Further, an initiator V-601 (a product of Wako Pure ChemicalIndustries, Ltd.) is added to and dissolved in the monomer solution inan amount of 8 mole % based on the total monomers. The resultantsolution is added dropwise to the Solvent 1 over 6 hours. After theconclusion of dropwise addition, reaction is made to continue at 80° C.for additional 2 hours. The reaction solution obtained is allowed tostand for cooling. Then, the reaction solution is poured into a mixtureof 1,800 ml of hexane and 200 ml of ethyl acetate, and powdery matterthus precipitated is filtered off and dried, thereby yielding 37 g ofResin (A1). The weight average molecular weight of Resin (A1) thusobtained is 5,500 as calculated in terms of standard polystyrene, andthe polydispersity (Mw/Mn) of Resin (A1) is 1.65.

In the manners similar to the above, Resins (A2) to (A8) aresynthesized.

Structural formulae of Resins (A2) to (A8) are illustrated below. Andthe ratio (by mole) between structural units, weight average molecularweight and polydispersity of each resin are summarized in Table 2.

TABLE 2 Resin (A) Ratio between Compound Structural Units Code Mw Mw/Mn(by mole) A1  5,500 1.65 40/25/35 A2  9,500 1.65 45/55 A3  5,500 1.6555/5/40 A4  8,200 1.68 55/5/40 A5  4,000 1.71 35/20/45 A6  8,500 1.8540/20/30/10 A7 13,500 1.75 40/5/45/10 A8  5,500 1.65 40/10/40/10

<Preparation of Resist Composition>

Resist compositions Ra1 to Ra10, Ra1′, Ra6′ and Rb1 are prepared bydissolving their respective combinations of ingredients in theirrespective solvents as shown in the following Table 3, and passing eachof the resultant solutions through a polyethylene filter having a poresize of 0.05 μm.

TABLE 3 Solvent Solids Resist Acid Generator Resin (A) Resin (D) BasicCompound Surfactant (ratio by Concentration Composition (parts by mass)(parts by mass) (parts by mass) (parts by mass) (100 ppm) weight) (mass%) Ra1 z62 A1 D-8 N-1 W-4 SL-1/SL-2 5.3 (5) (93.10) (1.40) (0.50)(70/30) Ra2 z57 A2 not mixed N-1 W-4 SL-1/SL-2 5.3 (5) (94.45) (0.55)(70/30) Ra3 z59 A3 D-11 N-1 W-4 SL-1/SL-2 5.3 (3.2) (90.20) (4.30)(0.50) (70/30) Ra4 z74 A4 D-14 N-2 W-3 SL-1/SL-2 7.5 (4.5) (93.30)(3.00) (0.50) (60/40) Ra5 z76 A5 D-15 N-2 W-2 SL-1/SL-2 5.3 (6.5)(93.35) (1.70) (0.45) (90/10) Ra6 z16 A6 D-20 N-1 W-1 SL-1/SL-2 5.3(5.0) (91.00) (2.00) (0.50) (80/20) Ra7 z17 A1 D-25 N-3 W-3 SL-1 5.3(4.5) (89.65) (5.00) (0.35) (100) Ra8 z53 A7 D-30 N-2 W-2 SL-2 5.7 (4.0)(94.42) (0.80) (0.28) (100) Ra9 z8/z46 A7 D-60 N-3 W-4 SL-1/SL-2 5.7(6.3/0.8) (94.50) (0.30) (0.40) (50/50) Ra10 z63 A8 D-74 N-1 W-4SL-1/SL-2 3.7 (4.8) (92.70) (0.50) (0.50) (70/30) Ra1′ z62 A1 D-8 N-1W-4 SL-1/SL-2 7.5 (5) (93.10) (1.40) (0.50) (70/30) Ra6′ z16 A6 D-20 N-1W-1 SL-1/SL-2 7.5 (5.0) (91.00) (2.00) (0.50) (80/20) Rb1 z20 A6 notmixed N-1 W-1 SL-1/SL-2 7.5 (5.0) (91.50) (0.50) (80/20) The symbols inTable 3 stand for the following compounds, respectively. N-1:N,N-Diphenylaniline N-2: Diazabicyclo[4.3.0]nonene N-3:4-Dimethylaminopyridine W-1: Megafac F176 (a fluorinated surfactant,produced by Dainippon Ink & Chemicals, Inc.) W-2: Megafac R08 (asurfactant containing both fluorine and silicon atoms, produced byDainippon Ink & Chemicals, Inc.) W-3: Polysiloxane polymer KP-341 (asilicon surfactant, produced by Shin-Etsu Chemical Co., Ltd.) W-4:PF6320 (a fluorinated surfactant, produced by OMNOVA Solutions Inc.)SL-1: Propylene glycol monomethyl ether acetate SL-2: Propylene glycolmonomethyl ether

In accordance with the methods mentioned hereinafter, evaluations aremade using the thus prepared resist compositions.

Example 1 Negative Development

An organic antireflective film ARC29A (a product of Nissan ChemicalIndustries, Ltd.) is applied to a silicon wafer surface, and baked at205° C. for 60 seconds, thereby forming a 78 nm-thick antireflectivefilm. On this film, the resist composition Ra1 is spin-coated, and bakedat 120° C. for 60 seconds, thereby forming a 150 nm-thick resist film.The thus obtained wafer is subjected to immersion exposure via a maskfor pattern formation, wherein purified water is used as the immersionliquid and PAS5500/1250i equipped with a lens of NA=0.85 (made by ASML)is used as an ArF excimer laser scanner. After the exposure, the waferis spun at revs of 2,000 rpm, and thereby the water remaining on thewafer is removed. Then, the wafer is subjected successively to 60seconds' heating at 120° C., 60 seconds' development (negativedevelopment) with butyl acetate (negative developer), rinse with1-hexanol, and 30 seconds' spinning at revs of 4,000 rpm. Thus, 80-nm(1:1) line-and-space resist patterns are formed.

Examples 2 to 10 and Comparative Example 1 Negative Development andChange in Resist Composition

80-nm (1:1) Line-and-space patterns are formed in the same manner as inExample 1, except that the resist composition is changed to Ra2 to Ra10and Rb1, respectively. In Example 10, however, the resist film thicknessis 100 nm.

Comparative Example 2 Positive Development Alone

An organic antireflective film ARC29A (a product of Nissan ChemicalIndustries, Ltd.) is applied to a silicon wafer surface, and baked at205° C. for 60 seconds, thereby forming a 78 nm-thick antireflectivefilm. On this film, the resist composition Ra1 is spin-coated, and bakedat 120° C. for 60 seconds, thereby forming a 150 nm-thick resist film.The thus obtained wafer is subjected to immersion exposure via a maskfor pattern formation, wherein purified water is used as an immersionliquid and PAS5500/1250i equipped with a lens of NA=0.85 (made by ASML)is used as an ArF excimer laser scanner. After the exposure, the waferis spun at revs of 2,000 rpm, and thereby the water remaining on thewafer is removed. Then, the wafer is subjected successively to 60seconds' heating at 120° C., 60 seconds' development (positivedevelopment) with a 2.38 mass % aqueous solution of tetramethylammoniumhydroxide (positive developer), rinse with purified water, and 30seconds' spinning at revs of 4,000 rpm. Thus, 80-nm (1:1) line-and-spaceresist patterns are formed.

Example 11 Combined Use of Negative Development and Positive Development

An organic antireflective film ARC29A (a product of Nissan ChemicalIndustries, Ltd.) is applied to a silicon wafer surface, and baked at205° C. for 60 seconds, thereby forming a 78 nm-thick antireflectivefilm. On this film, the resist composition Ra1 is spin-coated, and bakedat 120° C. for 60 seconds, thereby forming a 150 nm-thick resist film.The thus obtained wafer is subjected to immersion exposure via a maskfor pattern formation, wherein purified water is used as an immersionliquid and PAS5500/1250i equipped with a lens of NA=0.85 (made by ASML)is used as an ArF excimer laser scanner. After the exposure, the waferis spun at revs of 2,000 rpm, thereby undergoing removal of the waterremaining thereon, and further heated at 120° C. for 60 seconds. Then,the wafer is subjected to 60 seconds' development (positive development)with a 2.38 mass % aqueous solution of tetramethylammonium hydroxide(positive developer), and further to rinse with purified water. Thus,patterns with a pitch of 320 nm and a line width of 240 nm are formed.Next, the resultant wafer is subjected to 60 seconds' development(negative development) with butyl acetate (negative developer), furtherto rinse with 1-hexanol, and then to 30 seconds' spinning at revs of4,000 rpm. Thus, 80-nm (1:1) line-and-space resist patterns areobtained.

Example 12 Combined Use of Negative Development and Positive Development

An organic antireflective film ARC29A (a product of Nissan ChemicalIndustries, Ltd.) is applied to a silicon wafer surface, and baked at205° C. for 60 seconds, thereby forming a 78 nm-thick antireflectivefilm. On this film, the resist composition Ra1 is spin-coated, and bakedat 120° C. for 60 seconds, thereby forming a 150 nm-thick resist film.The thus obtained wafer is subjected to immersion exposure via a maskfor pattern formation, wherein purified water is used as an immersionliquid and PAS5500/12501 equipped with a lens of NA=0.85 (made by ASML)is used as an ArF excimer laser scanner. After the exposure, the waferis spun at revs of 2,000 rpm, thereby undergoing removal of the waterremaining thereon, and further heated at 120° C. for 60 seconds. Then,the wafer is subjected to 60 seconds' development (negative development)with butyl acetate (negative developer), further to rinse with1-hexanol, and then to 30 seconds' spinning at revs of 4,000 rpm. Thus,patterns with a pitch of 320 nm and a line width of 240 nm are formed.Next, the resultant wafer is subjected to 60 seconds' development(positive development) with a 2.38 mass % aqueous solution oftetramethylammonium hydroxide (positive developer), and further to rinsewith purified water. Thus, 80-nm (1:1) line-and-space resist patternsare obtained.

Examples 13 to 23 Negative Development and Change in DevelopmentCondition

80-nm (1:1) Line-and-space resist patterns are formed in the same manneras in Example 1, except that the combination of resist composition,negative developer and rinse liquid for negative development is changedto each of the combinations shown in Table 4.

Evaluation of Scum

With respect to the 80-nm (1:1) line-and-space patterns obtained in eachof Examples 1 to 23 and Comparative Examples 1 and 2, top surfaces ofline patterns and space areas are observed under a critical dimensionscanning electron microscope (S-9260, made by Hitachi Ltd.). Cases whereno resist residue is observed at all are rated as A, cases where almostno resist residue is observed are rated as B, cases where resistresidues are observed in small quantities are rated as C, and caseswhere resist residues are observed in considerable quantities are ratedas D. Results obtained are shown in Table 4.

Evaluation of Line Edge Roughness (LER)

A 80-nm (1:1) line-and-space pattern obtained in each of Examples 1 to23 and Comparative Examples 1 and 2 is observed under a criticaldimension scanning electron microscope (S-9260, made by Hitachi Ltd.),and the 80-nm line pattern is examined for distance from its edge linealong the length direction to a base line, on which the edge line shouldbe, at 50 different points on a 2-μm edge segment. And standarddeviation is determined from these distance measurements, and 3σ isfurther calculated. The smaller the value thus calculated, the betterthe performance. Results obtained are shown in Table 4.

Evaluation of 1n-Plane Uniformity of Line Width

By means of a critical dimension scanning electron microscope (S-9260,made by Hitachi Ltd.), line widths of 80-nm (1:1) line-and-space resistpatterns obtained by each of Examples 1 to 23 and Comparative Examples 1and 2 are measured at 50 points having a spacing of 2 mm. From thesemeasured values, standard deviation is determined and further 36 iscalculated. The smaller the value thus calculated, the better theperformance. Results obtained are shown in Table 4.

Evaluation of Receding Contact Angle with Respect to Water

Each of the resist compositions shown in Table 3 is applied to a siliconwafer surface by means of a spin coater, and the coating solvent usedtherein is dried by 60 seconds' heating on a 120° C. hot plate. Thus,resist film having a thickness of 150 nm is formed. The contact angle ofeach resist film with respect to purified water is measured with acontact angle meter DM500 made by Kyowa Interface Science Co., Ltd. Themeasurement is carried out under conditions that the temperature is 25°C. and the humidity is 50%.

Evaluation of Following Capability of Water

A negative resist composition prepared is applied to a silicon wafersurface, and baked at 120° C. for 60 seconds, thereby forming resistfilm having a thickness of 150 nm. Then, as shown in FIG. 4, a spacebetween the resist film-coated wafer 1 and a quartz glass substrate 3 isfilled with purified water 2. In this condition, the quartz glasssubstrate 3 is moved (scanned) in parallel with the surface of theresist film-coated wafer 1, and the state of purified water followingthe parallel movement is observed by the naked eye. The scanning speedof the quartz glass substrate 3 is increased gradually until thepurified water cannot follow the scanning speed of the quartz glasssubstrate 3 and droplets thereof comes to remain on the receding side.By determining this limiting scanning speed (unit: mm/sec), evaluationof following capability of water is made. The greater this limitingspeed of possible scanning, the higher speed of scanning the water canfollow, which indicates that water has the better following capabilityon the resist film.

TABLE 4 Rinse liquid for Receding In-Plane Following Negative ContactUniformity Capability Resist Negative Developer Development PositiveAngle LER of Line of Water Composition (ratio by weight) (ratio byweight) Development (degree) Scum (nm) Width (nm) (mm/sec) Example 1 Ra1Butyl acetate (100) 1-Hexanol (100) Not performed 90 A 3.6 5.0 500Example 2 Ra2 Butyl acetate (100) 1-Hexanol (100) Not performed 70 C 7.27.5 300 Example 3 Ra3 Butyl acetate (100) 1-Hexanol (100) Not performed94 C 6.0 5.9 500 Example 4 Ra4 Butyl acetate (100) 1-Hexanol (100) Notperformed 82 A 7.6 4.3 450 Example 5 Ra5 Butyl acetate (100) 1-Hexanol(100) Not performed 72 B 3.8 3.0 300 Example 6 Ra6 Butyl acetate (100)1-Hexanol (100) Not performed 77 A 3.7 4.7 400 Example 7 Ra7 Butylacetate (100) 1-Hexanol (100) Not performed 90 A 6.1 6.5 500 Example 8Ra8 Butyl acetate (100) 1-Hexanol (100) Not performed 80 A 3.6 4.6 450Example 9 Ra9 Butyl acetate (100) 1-Hexanol (100) Not performed 70 B 3.23.5 300 Example 10 Ra10 Butyl acetate (100) 1-Hexanol (100) Notperformed 71 B 3.1 3.5 300 Example 11 Ra1 Butyl acetate (100) 1-Hexanol(100) performed 90 A 4.3 3.9 500 Example 12 Ra1 Butyl acetate (100)1-Hexanol (100) performed 90 A 4.3 4.3 500 Example 13 Ra1 Isoamylacetate (100) 1-Hexanol (100) Not performed 90 A 3.3 5.1 500 Example 14Ra1 Methyl isobutyl ketone (100) 1-Hexanol (100) Not performed 90 A 4.44.3 500 Example 15 Ra1 2-Hexanone (100) 1-Hexanol (100) Not perfonned 90A 4.2 3.5 500 Example 16 Ra1 n-Butyl ether (100) 1-Hexanol (100) Notperfonned 90 A 3.9 4.9 500 Example 17 Ra1′ Methyl ethyl ketone (100)Decane (100) Not perfonned 90 A 7.7 6.7 500 Example 18 Ra1′ Dipropylether (100) Decane (100) Not performed 90 A 7.6 7.4 500 Example 19 Ra1Butyl acetate/2-Hexanone 1-Hexanol (100) Not performed 90 A 4.2 4.3 500(80/20) Example 20 Ra1 Isoamyl acetate/n-Butyl 1-Hexanol (100) Notperformed 90 A 4.3 5.1 500 ether (70/30) Example 21 Ra1 Isoamyl acetate(100) 2-Heptanol (100) Not performed 90 A 3.2 3.8 500 Example 22 Ra1Isoamyl acetate (100) Decane (100) Not performed 90 A 3.3 4.4 500Example 23 Ra1 Isoamyl acetate (100) 2-Heptanol/ Not performed 90 A 3.15.1 500 Decane (50/50) Compar. Rb1 Butyl acetate (100) 1-Hexanol (100)Not performed 35 D 11.5 11.2 100 Example 1 Compar. Ra6′ Not used Notused performed 77 D 10.0 10.1 400 Example 2

The term “ratio by weight” in Table 4 represents the ratio by weightbetween two kinds of organic solvents used in a mixed state as anegative developer or a rinse liquid for negative development. Herein,the ratio by weight in the case of using only one kind of organicsolvent as a negative developer or a rinse liquid for negativedevelopment is 100. In Comparative Example 2, on the other hand, neithernegative development process nor rinse process after negativedevelopment is carried out, but the positive development process iscarried out using an aqueous solution of tetramethylammonium hydroxide(2.38 mass %) and the rinse process using purified water is carried outafter the positive development.

Vapor pressures and boiling points of the solvents constituting thenegative developers for negative development and the rinse liquids usedin Examples are shown in Table 5.

TABLE 5 Vapor Pressure Boiling at 20° C. Point Name of Solvent (kPa) (°C.) Negative Developer Butyl acetate 1.2 126 Isoamyl acetate 0.53 142Methyl isobutyl ketone 2.1 117-118 2-Hexanone 0.36 126-128 Methyl ethylketone 10.5 80 Dipropyl ether 8.33  88-90  n-Butyl ether 0.64 142 Rinseliquid for 1-Hexanol 0.13 157 Negative Development 2-Heptanol 0.133150-160 Decane 0.17 174.2

As is evident from the results obtained in Examples, the resistcompositions used for negative development in accordance with theinvention allow consistent formation of high-accuracy fine patterns thatare prevented from suffering scum, reduced in line edge roughness andsatisfactory in in-plane uniformity of line width. In addition, it isalso apparent that the resist compositions used for negative developmentin accordance with the invention ensure an immersion liquid goodfollowing capability in immersion exposure.

In accordance with the present pattern formation method, patters reducedin scum appearing after development and improved in line edge roughnessand in-plane uniformity of line width can be formed with high precision.

The entire disclosure of each and every foreign patent application fromwhich the benefit of foreign priority has been claimed in the presentapplication is incorporated herein by reference, as if fully set forth.

1. A method for producing an electronic device, comprising a method offorming patterns, wherein the method of forming patterns comprises: (a)coating a substrate with a resist composition for negative developmentto form a resist film having a receding contact angle of 70 degrees orabove with respect to water, wherein the resist composition for negativedevelopment contains a resin capable of increasing its polarity by theaction of an acid and becomes more soluble in a positive developer whichis an alkali developer and becomes less soluble in a negative developercontaining an organic solvent upon irradiation with an actinic ray orradiation, (b) exposing the resist film via an immersion medium, and (c)performing development with the negative developer.
 2. The method forproducing an electronic device of claim 1, wherein the resistcomposition for negative development comprises: (A) the resin capable ofincreasing the polarity by the action of an acid, which becomes moresoluble in the positive developer and less soluble in the negativedeveloper upon irradiation with an actinic ray or radiation, (B) acompound capable of generating an acid upon irradiation with an actinicray or radiation, (C) a solvent, and (D) a resin having at least eithera fluorine atom or a silicon atom.
 3. A method for producing anelectronic device, comprising a method of forming patterns, wherein themethod of forming patterns comprises: (a′) coating a substrate with aresist composition for negative development to form a resist film,wherein the resist composition contains a resin capable of increasingits polarity by the action of an acid and becomes more soluble in apositive developer which is an alkali developer and less soluble in anegative developer containing an organic solvent upon irradiation withan actinic ray or radiation, (b) exposing the resist film via animmersion medium, and (c) performing development with the negativedeveloper. wherein the resist composition for negative developmentcomprises: (A) the resin capable of increasing the polarity by theaction of an acid, which becomes more soluble in the positive developerand less soluble in the negative developer upon irradiation with anactinic ray or radiation, (B) a compound capable of generating an acidupon irradiation with an actinic ray or radiation, (C) a solvent, and(D) a resin having at least either a fluorine atom or a silicon atom. 4.The method for producing an electronic device of claim 2, wherein theresin (D) has a group represented by the following formula (F3a):

wherein each of R_(62a) and R_(63a) independently represents an alkylgroup at least one hydrogen atom of which is substituted with a fluorineatom, and R_(62a) and R_(63a) may combine with each other to form aring, and R_(64a) represents a hydrogen atom, a fluorine atom or analkyl group.
 5. The method for producing an electronic device of claim3, wherein the resin (D) has a group represented by the followingformula (F3a):

wherein each of R_(62a) and R_(63a) independently represents an alkylgroup at least one hydrogen atom of which is substituted with a fluorineatom, and R_(62a) and R_(63a) may combine with each other to form aring, and R_(64a) represents a hydrogen atom, a fluorine atom or analkyl group.
 6. The method for producing an electronic device of claim2, wherein the resin (D) has a group represented by any of the followingformulae (CS-1) to (CS-3):

wherein each of R₁₂ to R₂₆ independently represents a straight-chainalkyl group, a branched alkyl group, or a cycloalkyl group, each of L₃to L₅ represents a single bond or a divalent linkage group, and nrepresents an integer of 1 to
 5. 7. The method for producing anelectronic device of claim 3, wherein the resin (D) has a grouprepresented by any of the following formulae (CS-1) to (CS-3):

wherein each of R₁₂ to R₂₆ independently represents a straight-chainalkyl group, a branched alkyl group, or a cycloalkyl group, each of L₃to L₅ represents a single bond or a divalent linkage group, and nrepresents an integer of 1 to
 5. 8. The method for producing anelectronic device of claim 1, wherein the negative developer in theprocess (c) of performing development contains an organic solvent. 9.The method for producing an electronic device of claim 3, wherein thenegative developer in the process (c) of performing development containsan organic solvent.
 10. The method for producing an electronic device ofclaim 1, wherein the vapor pressure of the negative developer at 20° C.is 5 kPa or below.
 11. The method for producing an electronic device ofclaim 1, wherein the organic solvent which the negative developercontains is at least one organic solvent selected from the groupconsisting of a ketone solvent, an ester solvent, an alcohol solvent, anamide solvent, an ether solvent, and a hydrocarbon solvent.
 12. Themethod for producing an electronic device of claim 1, wherein the methodof forming patterns further comprises: performing cleaning with a rinseliquid containing an organic solvent after development with the negativedeveloper.
 13. A method for producing an electronic device, comprising amethod of forming patterns, wherein the method of forming patternscomprises: coating with a resist composition for negative development toform a resist film, wherein the resist composition for negativedevelopment contains a resin capable of increasing its polarity by theaction of an acid and becomes more soluble in a positive developer whichis an alkali developer and becomes less soluble in a negative developercontaining an organic solvent upon irradiation with an actinic ray orradiation, exposing the resist film via an immersion medium, andperforming development with the negative developer, wherein the resistcomposition for negative development comprises: (A) the resin capable ofincreasing the polarity by the action of an acid, which becomes moresoluble in the positive developer and less soluble in the negativedeveloper upon irradiation with an actinic ray or radiation, (B) acompound capable of generating an acid upon irradiation with an actinicray or radiation, (C) a solvent, and (D) a resin having at least eithera fluorine atom or a silicon atom, wherein the amount of the component(D) is 0.1 mass % or more, based on the total solids in the resistcomposition.
 14. The method for producing an electronic device of claim13, wherein the resin (D) has a group represented by the followingformula (F3a):

wherein in formula (F3a) each of R_(62a) and R_(63a) independentlyrepresents an alkyl group at least one hydrogen atom of which issubstituted with a fluorine atom, and R_(62a) and R_(63a) may combinewith each other to form a ring, and R_(64a) represents a hydrogen atom,a fluorine atom or an alkyl group.
 15. The method for producing anelectronic device of claim 13, wherein the resin (D) has a grouprepresented by any of the following formulae (CS-1) to (CS-3):

wherein in formulae (CS-1) to (CS-3) each of R₁₂ to R₂₆ independentlyrepresents a straight-chain alkyl group, a branched alkyl group, or acycloalkyl group, each of L₃ to L₅ represents a single bond or adivalent linkage group, and n represents an integer of 1 to
 5. 16. Themethod for producing an electronic device of claim 13, wherein themethod of forming patterns comprises: developing the resist film afterexposure with the positive development at least either after or beforedevelopment with the negative development.
 17. The method for producingan electronic device of claim 13, wherein the organic solvent which thenegative developer contains is at least one organic solvent selectedfrom the group consisting of a ketone solvent, an ester solvent and anether solvent.
 18. The method for producing an electronic device ofclaim 13, wherein the method of forming patterns comprises: performingcleaning with a rinse liquid containing an organic solvent afterdevelopment with the negative developer.
 19. The method for producing anelectronic device of claim 13, wherein the exposure is performed withlight having a wavelength of 200 nm or shorter.
 20. The method forproducing an electronic device of claim 13, wherein the immersion mediumis water.
 21. The method for producing an electronic device of claim 13,wherein the amount of the component (D) of the resist composition is 0.1to 5 mass %, based on the total solids in the resist composition. 22.The method for producing an electronic device of claim 13, wherein thecomponent (A) of the resist composition is a resin having an alicyclichydrocarbon structure.
 23. The method for producing an electronic deviceof claim 17, wherein the organic solvent which the negative developercontains is a ketone solvent.
 24. The method for producing an electronicdevice of claim 17, wherein the organic solvent which the negativedeveloper contains is an ester solvent.
 25. The method for producing anelectronic device of claim 13, wherein the component (A) has no aromaticgroup.
 26. The method for producing an electronic device of claim 22,wherein the component (A) is an alicyclic hydrocarbon-containingacid-decomposable resin having a repeating unit having an alicyclichydrocarbon-containing partial structure represented by any of thefollowing formula (pI) or (pII):

wherein R₁₁ represents a methyl group, an ethyl group, an n-propylgroup, an isopropyl group, an n-butyl group, an isobutyl group or asec-butyl group, and Z represents atoms forming a cycloalkyl grouptogether with the carbon atom; R₁₂ to R₁₄ each represent astraight-chain or branched alkyl group having 1 to 4 carbon atom(s), ora cycloalkyl group independently, provided that at least one of R₁₂ toR₁₄ represents a cycloalkyl group.
 27. The method for producing anelectronic device of claim 13, wherein the component (D) is a resinhaving repeating units of at least one kind selected from thoserepresented by the following formulae (C-I) to (C-IV):

wherein in the formulae (C-I) to (C-IV), R₁ to R₃, which are mutuallyindependent, each represent a hydrogen atom, a fluorine atom, astraight-chain or branched alkyl group having 1 to 4 carbon atom(s), ora straight-chain or branched fluoroalkyl group having 1 to 4 carbonatom(s), W₁ and W₂ each represent an organic group having at leasteither a fluorine or silicon atom, R₄ to R₇, which are mutuallyindependent, each represent a hydrogen atom, a fluorine atom, astraight-chain or branched alkyl group having 1 to 4 carbon atom(s), ora straight-chain or branched fluoroalkyl group having 1 to 4 carbonatom(s), provided that at least one of the substituents R₄ to R₇ is afluorine atom, R₄ and R₅, or R₆ and R₇ may combine with each other toform a ring, R₈ represents a hydrogen atom, or a straight-chain orbranched alkyl group having 1 to 4 carbon atom(s), R₉ represents astraight-chain or branched alkyl group having 1 to 4 carbon atom(s), ora straight-chain or branched fluoroalkyl group having 1 to 4 carbonatom(s), L₁ and L₂ each represents a single bond or a divalent linkagegroup, Q represents a mononuclear or polynuclear cyclic aliphatic group.28. The method for producing an electronic device of claim 27, whereinthe component (D) has a repeating unit represented by formula (C-I), andthe formula (C-I) is any of the following formulae (C-Ia) to (C-Id):

wherein in the formulae (C-Ia) to (C-Id), R₁₀ and R₁₁ each represent ahydrogen atom, a fluorine atom, a straight-chain or branched alkyl grouphaving 1 to 4 carbon atom(s), or a straight-chain or branchedfluoroalkyl group having 1 to 4 carbon atom(s), W₃ to W₆ each representsan organic group having at least either one or more fluorine atoms, orone or more silicon atoms.
 29. The method for producing an electronicdevice of claim 13, wherein the negative developer containing an organicsolvent is a developer consisting essentially of an organic solvent.